Why would someone use WHERE 1 1 AND conditions in a SQL clause

Question

Why would someone use WHERE 1 1 AND  lt conditions gt  in a SQL clause  Either SQL obtained through concatenated strings  either view definition   I ve seen somewhere that this would be used to protect against SQL Injection  but it seems very weird   If there is injection WHERE 1   1 AND injected OR 1 1 would have the same result as injected OR 1 1   Later edit  What about the usage in a view definition     Thank you for your answers   Still  I don t understand why would someone use this construction for defining a view  or use it inside a stored procedure   Take this for example   CREATE VIEW vTest AS SELECT FROM Table WHERE 1 1 AND table Field Value

User · Answer

I first came across this back with ADO and classic asp, the answer i got was: performance. if you do a straight

Select * from tablename

and pass that in as an sql command/text you will get a noticeable performance increase with the

Where 1=1

added, it was a visible difference. something to do with table headers being returned as soon as the first condition is met, or some other craziness, anyway, it did speed things up.

User · Answer

Having review all the answers i decided to perform some experiment like  SELECT   FROM MyTable  WHERE 1 1   Then i checked with other numbers  WHERE 2 2 WHERE 10 10 WHERE 99 99   ect Having done all the checks  the query run town is the same  even without the where clause  I am not a fan of the syntax

User · Answer

This is useful in a case where you have to use dynamic query in which in where  clause you have to append some filter options  Like if you include options 0 for status is inactive  1 for active  Based from the options  there is only two available options 0 and 1  but if you want to display All records  it is handy to include in where close 1 1  See below sample   Declare  SearchValue    varchar 8   Declare  SQLQuery varchar max      Select  FirstName        LastName        MiddleName        BirthDate   Case     when  Status    0 then   Inactive       when  Status    1 then   Active   end as  Status    Declare  SearchOption nvarchar 100  If   SearchValue    Active   Begin     Set  SearchOption     Where a  Status    1  End  If   SearchValue    Inactive   Begin     Set  SearchOption     Where a  Status    0  End  If   SearchValue    All   Begin     Set  SearchOption     Where 1 1  End  Set  SQLQuery    SQLQuery    SearchOption  Exec  SQLQuery

User · Answer

Indirectly Relevant  when 1 2 is used   CREATE TABLE New table name  as  select    FROM Old table name  WHERE 1   2    this will create a new table with same schema as old table   Very handy if you want to load some data for compares

User · Answer

I ve seen it used when the number of conditions can be variable    You can concatenate conditions using an   AND   string  Then  instead of counting the number of conditions you re passing in  you place a  WHERE 1 1  at the end of your stock SQL statement and throw on the concatenated conditions   Basically  it saves you having to do a test for conditions and then add a  WHERE  string before them

User · Answer

Making  quot where 1 1 quot  the standard for all your queries also makes it trivially easy to validate the sql by replacing it with where 1   0  handy when you have batches of commands files  Also makes it trivially easy to find the end of the end of the from join section of any query  Even queries with sub-queries if properly indented

User · Answer

If you came here searching for WHERE 1  note that WHERE 1 and WHERE 1 1 are identical  WHERE 1 is used rarely because some database systems reject it considering WHERE 1 not really being boolean

User · Answer

I ve seen it used when the number of conditions can be variable    You can concatenate conditions using an   AND   string  Then  instead of counting the number of conditions you re passing in  you place a  WHERE 1 1  at the end of your stock SQL statement and throw on the concatenated conditions   Basically  it saves you having to do a test for conditions and then add a  WHERE  string before them

User · Answer

Seems like a lazy way to always know that your WHERE clause is already defined and allow you to keep adding conditions without having to check if it is the first one

User · Answer

I found usefull this pattern when I m testing or doublechecking things on the database  so I can comment very quickly other conditions   CREATE VIEW vTest AS SELECT FROM Table WHERE 1 1  AND Table Field Value AND Table IsValid true   turns into   CREATE VIEW vTest AS SELECT FROM Table WHERE 1 1  --AND Table Field Value --AND Table IsValid true

User · Answer

I ve seen it used when the number of conditions can be variable    You can concatenate conditions using an   AND   string  Then  instead of counting the number of conditions you re passing in  you place a  WHERE 1 1  at the end of your stock SQL statement and throw on the concatenated conditions   Basically  it saves you having to do a test for conditions and then add a  WHERE  string before them

User · Answer

I first came across this back with ADO and classic asp, the answer i got was: performance. if you do a straight

Select * from tablename

and pass that in as an sql command/text you will get a noticeable performance increase with the

Where 1=1

added, it was a visible difference. something to do with table headers being returned as soon as the first condition is met, or some other craziness, anyway, it did speed things up.

User · Answer

Why would someone use WHERE 1 1 AND  lt proper conditions gt    I ve seen homespun frameworks do stuff like this  blush   as this allows lazy parsing practices to be applied to both the WHERE and AND Sql keywords   For example  I m using C  as an example here   consider the conditional parsing of the following predicates in a Sql query string builder   var sqlQuery    SELECT   FROM FOOS WHERE 1   1  if  shouldFilterForBars        sqlQuery   sqlQuery     AND Bars  gt  3     if  shouldFilterForBaz        sqlQuery   sqlQuery     AND Baz  lt  12       The  benefit  of WHERE 1   1 means that no special code is needed    For AND - whether zero  one or both predicates  Bars and Baz s  should be applied  which would determine whether the first AND is required  Since we already have at least one predicate with the 1   1  it means AND is always OK  For no predicates at all - In the case where there are ZERO predicates  then the WHERE must be dropped  But again  we can be lazy  because we are again guarantee of at least one predicate    This is obviously a bad idea and would recommend using an established data access framework or ORM for parsing optional and conditional predicates in this way

User · Answer

Just adding a example code to Greg s answer   dim sqlstmt as new StringBuilder sqlstmt add  SELECT   FROM Products   sqlstmt add   WHERE 1 1          From now on you don t have to worry if you must       append AND or WHERE because you know the WHERE is there If ProductCategoryID  lt  gt  0 then   sqlstmt AppendFormat   AND ProductCategoryID    0    trim ProductCategoryID   end if If MinimunPrice  gt  0 then   sqlstmt AppendFormat   AND Price  gt    0    trim MinimunPrice   end if

User · Answer

Here is a use case    however I am not too concerned with the technicalities of why I should or not use 1   1  I am writing a function  using pyodbc to retrieve some data from SQL Server  I was looking for a way to force a filler after the where keyword in my code  This was a great suggestion indeed   if  where         where    1 1              cur execute f select  predicate  from  table name  where   where      The reason is because I could not implement the keyword  where  together inside the  where clause variable  So  I think using any dummy condition that evaluates to true would do as a filler

User · Answer

Actually  I ve seen this sort of thing used in BIRT reports   The query passed to the BIRT runtime is of the form   select a b c from t where a       and the     is replaced at runtime by an actual parameter value selected from a drop-down box   The choices in the drop-down are given by   select distinct a from t union all select     from sysibm sysdummy1   so that you get all possible values plus       If the user selects     from the drop down box  meaning all values of a should be selected   the query has to be modified  by Javascript  before being run   Since the     is a positional parameter and MUST remain there for other things to work  the Javascript modifies the query to be   select a b c from t where   a      or  1  1     That basically removes the effect of the where clause while still leaving the positional parameter in place   I ve also seen the AND case used by lazy coders whilst dynamically creating an SQL query   Say you have to dynamically create a query that starts with select   from t and checks    the name is Bob  and the salary is    20 000   some people would add the first with a WHERE and subsequent ones with an AND thus   select   from t where name    Bob  and salary  gt  20000   Lazy programmers  and that s not necessarily a bad trait  wouldn t distinguish between the added conditions  they d start with select   from t where 1 1 and just add AND clauses after that   select   from t where 1 1 and name    Bob  and salary  gt  20000

User · Answer

Having review all the answers i decided to perform some experiment like  SELECT   FROM MyTable  WHERE 1 1   Then i checked with other numbers  WHERE 2 2 WHERE 10 10 WHERE 99 99   ect Having done all the checks  the query run town is the same  even without the where clause  I am not a fan of the syntax

User · Answer

Using a predicate like 1 1 is a normal hint sometimes used to force the access plan to use or not use an index scan   The reason why this is used is when you are using a multi-nested joined query with many predicates in the where clause where sometimes even using all of the indexes causes the access plan to read each table - a full table scan   This is just 1 of many hints used by DBAs to trick a dbms into using a more efficient path   Just don t throw one in  you need a dba to analyze the query since it doesn t always work

User · Answer

Actually  I ve seen this sort of thing used in BIRT reports   The query passed to the BIRT runtime is of the form   select a b c from t where a       and the     is replaced at runtime by an actual parameter value selected from a drop-down box   The choices in the drop-down are given by   select distinct a from t union all select     from sysibm sysdummy1   so that you get all possible values plus       If the user selects     from the drop down box  meaning all values of a should be selected   the query has to be modified  by Javascript  before being run   Since the     is a positional parameter and MUST remain there for other things to work  the Javascript modifies the query to be   select a b c from t where   a      or  1  1     That basically removes the effect of the where clause while still leaving the positional parameter in place   I ve also seen the AND case used by lazy coders whilst dynamically creating an SQL query   Say you have to dynamically create a query that starts with select   from t and checks    the name is Bob  and the salary is    20 000   some people would add the first with a WHERE and subsequent ones with an AND thus   select   from t where name    Bob  and salary  gt  20000   Lazy programmers  and that s not necessarily a bad trait  wouldn t distinguish between the added conditions  they d start with select   from t where 1 1 and just add AND clauses after that   select   from t where 1 1 and name    Bob  and salary  gt  20000

User · Answer

If the list of conditions is not known at compile time and is instead built at run time  you don t have to worry about whether you have one or more than one condition  You can generate them all like   and  lt condition gt    and concatenate them all together  With the 1 1 at the start  the initial and has something to associate with   I ve never seen this used for any kind of injection protection  as you say it doesn t seem like it would help much  I have seen it used as an implementation convenience  The SQL query engine will end up ignoring the 1 1 so it should have no performance impact

User · Answer

1   1 expression is commonly used in generated sql code  This expression can simplify sql generating code reducing number of conditional statements

User · Answer

Seems like a lazy way to always know that your WHERE clause is already defined and allow you to keep adding conditions without having to check if it is the first one

User · Answer

Seems like a lazy way to always know that your WHERE clause is already defined and allow you to keep adding conditions without having to check if it is the first one

User · Answer

Making  quot where 1 1 quot  the standard for all your queries also makes it trivially easy to validate the sql by replacing it with where 1   0  handy when you have batches of commands files  Also makes it trivially easy to find the end of the end of the from join section of any query  Even queries with sub-queries if properly indented

User · Answer

1   1 expression is commonly used in generated sql code  This expression can simplify sql generating code reducing number of conditional statements

User · Answer

If you came here searching for WHERE 1  note that WHERE 1 and WHERE 1 1 are identical  WHERE 1 is used rarely because some database systems reject it considering WHERE 1 not really being boolean

User · Answer

If the list of conditions is not known at compile time and is instead built at run time  you don t have to worry about whether you have one or more than one condition  You can generate them all like   and  lt condition gt    and concatenate them all together  With the 1 1 at the start  the initial and has something to associate with   I ve never seen this used for any kind of injection protection  as you say it doesn t seem like it would help much  I have seen it used as an implementation convenience  The SQL query engine will end up ignoring the 1 1 so it should have no performance impact

User · Answer

where 1 0  This is done to check if the table exists  Don t know why 1 1 is used

User · Answer

Just adding a example code to Greg s answer   dim sqlstmt as new StringBuilder sqlstmt add  SELECT   FROM Products   sqlstmt add   WHERE 1 1          From now on you don t have to worry if you must       append AND or WHERE because you know the WHERE is there If ProductCategoryID  lt  gt  0 then   sqlstmt AppendFormat   AND ProductCategoryID    0    trim ProductCategoryID   end if If MinimunPrice  gt  0 then   sqlstmt AppendFormat   AND Price  gt    0    trim MinimunPrice   end if

User · Answer

I found usefull this pattern when I m testing or doublechecking things on the database  so I can comment very quickly other conditions   CREATE VIEW vTest AS SELECT FROM Table WHERE 1 1  AND Table Field Value AND Table IsValid true   turns into   CREATE VIEW vTest AS SELECT FROM Table WHERE 1 1  --AND Table Field Value --AND Table IsValid true

User · Answer

If the list of conditions is not known at compile time and is instead built at run time  you don t have to worry about whether you have one or more than one condition  You can generate them all like   and  lt condition gt    and concatenate them all together  With the 1 1 at the start  the initial and has something to associate with   I ve never seen this used for any kind of injection protection  as you say it doesn t seem like it would help much  I have seen it used as an implementation convenience  The SQL query engine will end up ignoring the 1 1 so it should have no performance impact

User · Answer

I do this usually when I am building dynamic SQL for a report which has many dropdown values a user can select  Since the user may or may not select the values from each dropdown  we end up getting a hard time figuring out which condition was the first where clause  So we pad up the query with a where 1 1 in the end and add all where clauses after that   Something like  select column1  column2 from my table where 1 1  name   age     Then we would build the where clause like this and pass it as a parameter value  string name whereClause  ddlName SelectedIndex  gt  0    AND name      ddlName SelectedValue              As the where clause selection are unknown to us at runtime  so this helps us a great deal in finding whether to include an  AND  or  WHERE

User · Answer

Why would someone use WHERE 1 1 AND  lt proper conditions gt    I ve seen homespun frameworks do stuff like this  blush   as this allows lazy parsing practices to be applied to both the WHERE and AND Sql keywords   For example  I m using C  as an example here   consider the conditional parsing of the following predicates in a Sql query string builder   var sqlQuery    SELECT   FROM FOOS WHERE 1   1  if  shouldFilterForBars        sqlQuery   sqlQuery     AND Bars  gt  3     if  shouldFilterForBaz        sqlQuery   sqlQuery     AND Baz  lt  12       The  benefit  of WHERE 1   1 means that no special code is needed    For AND - whether zero  one or both predicates  Bars and Baz s  should be applied  which would determine whether the first AND is required  Since we already have at least one predicate with the 1   1  it means AND is always OK  For no predicates at all - In the case where there are ZERO predicates  then the WHERE must be dropped  But again  we can be lazy  because we are again guarantee of at least one predicate    This is obviously a bad idea and would recommend using an established data access framework or ORM for parsing optional and conditional predicates in this way

User · Answer

where 1 0  This is done to check if the table exists  Don t know why 1 1 is used

User · Answer

Using a predicate like 1 1 is a normal hint sometimes used to force the access plan to use or not use an index scan   The reason why this is used is when you are using a multi-nested joined query with many predicates in the where clause where sometimes even using all of the indexes causes the access plan to read each table - a full table scan   This is just 1 of many hints used by DBAs to trick a dbms into using a more efficient path   Just don t throw one in  you need a dba to analyze the query since it doesn t always work

User · Answer

While I can see that 1 1 would be useful for generated SQL  a technique I use in PHP is to create an array of clauses and then do  implode    AND     clauses     thus avoiding the problem of having a leading or trailing AND  Obviously this is only useful if you know that you are going to have at least one clause

User · Answer

1   1 expression is commonly used in generated sql code  This expression can simplify sql generating code reducing number of conditional statements

User · Answer

1   1 expression is commonly used in generated sql code  This expression can simplify sql generating code reducing number of conditional statements

User · Answer

I do this usually when I am building dynamic SQL for a report which has many dropdown values a user can select  Since the user may or may not select the values from each dropdown  we end up getting a hard time figuring out which condition was the first where clause  So we pad up the query with a where 1 1 in the end and add all where clauses after that   Something like  select column1  column2 from my table where 1 1  name   age     Then we would build the where clause like this and pass it as a parameter value  string name whereClause  ddlName SelectedIndex  gt  0    AND name      ddlName SelectedValue              As the where clause selection are unknown to us at runtime  so this helps us a great deal in finding whether to include an  AND  or  WHERE

User · Answer

Here is a use case    however I am not too concerned with the technicalities of why I should or not use 1   1  I am writing a function  using pyodbc to retrieve some data from SQL Server  I was looking for a way to force a filler after the where keyword in my code  This was a great suggestion indeed   if  where         where    1 1              cur execute f select  predicate  from  table name  where   where      The reason is because I could not implement the keyword  where  together inside the  where clause variable  So  I think using any dummy condition that evaluates to true would do as a filler

User · Answer

Seems like a lazy way to always know that your WHERE clause is already defined and allow you to keep adding conditions without having to check if it is the first one

User · Answer

This is useful in a case where you have to use dynamic query in which in where  clause you have to append some filter options  Like if you include options 0 for status is inactive  1 for active  Based from the options  there is only two available options 0 and 1  but if you want to display All records  it is handy to include in where close 1 1  See below sample   Declare  SearchValue    varchar 8   Declare  SQLQuery varchar max      Select  FirstName        LastName        MiddleName        BirthDate   Case     when  Status    0 then   Inactive       when  Status    1 then   Active   end as  Status    Declare  SearchOption nvarchar 100  If   SearchValue    Active   Begin     Set  SearchOption     Where a  Status    1  End  If   SearchValue    Inactive   Begin     Set  SearchOption     Where a  Status    0  End  If   SearchValue    All   Begin     Set  SearchOption     Where 1 1  End  Set  SQLQuery    SQLQuery    SearchOption  Exec  SQLQuery

User · Answer

Here s a closely related example  using a SQL MERGE statement to update the target tabled using all values from the source table where there is no common attribute on which to join on e g    MERGE INTO Circles    USING                  SELECT pi          FROM Constants         AS SourceTable    ON 1   1 WHEN MATCHED THEN    UPDATE      SET circumference   2   SourceTable pi   radius

User · Answer

If the list of conditions is not known at compile time and is instead built at run time  you don t have to worry about whether you have one or more than one condition  You can generate them all like   and  lt condition gt    and concatenate them all together  With the 1 1 at the start  the initial and has something to associate with   I ve never seen this used for any kind of injection protection  as you say it doesn t seem like it would help much  I have seen it used as an implementation convenience  The SQL query engine will end up ignoring the 1 1 so it should have no performance impact

User · Answer

Actually  I ve seen this sort of thing used in BIRT reports   The query passed to the BIRT runtime is of the form   select a b c from t where a       and the     is replaced at runtime by an actual parameter value selected from a drop-down box   The choices in the drop-down are given by   select distinct a from t union all select     from sysibm sysdummy1   so that you get all possible values plus       If the user selects     from the drop down box  meaning all values of a should be selected   the query has to be modified  by Javascript  before being run   Since the     is a positional parameter and MUST remain there for other things to work  the Javascript modifies the query to be   select a b c from t where   a      or  1  1     That basically removes the effect of the where clause while still leaving the positional parameter in place   I ve also seen the AND case used by lazy coders whilst dynamically creating an SQL query   Say you have to dynamically create a query that starts with select   from t and checks    the name is Bob  and the salary is    20 000   some people would add the first with a WHERE and subsequent ones with an AND thus   select   from t where name    Bob  and salary  gt  20000   Lazy programmers  and that s not necessarily a bad trait  wouldn t distinguish between the added conditions  they d start with select   from t where 1 1 and just add AND clauses after that   select   from t where 1 1 and name    Bob  and salary  gt  20000

User · Answer

Actually  I ve seen this sort of thing used in BIRT reports   The query passed to the BIRT runtime is of the form   select a b c from t where a       and the     is replaced at runtime by an actual parameter value selected from a drop-down box   The choices in the drop-down are given by   select distinct a from t union all select     from sysibm sysdummy1   so that you get all possible values plus       If the user selects     from the drop down box  meaning all values of a should be selected   the query has to be modified  by Javascript  before being run   Since the     is a positional parameter and MUST remain there for other things to work  the Javascript modifies the query to be   select a b c from t where   a      or  1  1     That basically removes the effect of the where clause while still leaving the positional parameter in place   I ve also seen the AND case used by lazy coders whilst dynamically creating an SQL query   Say you have to dynamically create a query that starts with select   from t and checks    the name is Bob  and the salary is    20 000   some people would add the first with a WHERE and subsequent ones with an AND thus   select   from t where name    Bob  and salary  gt  20000   Lazy programmers  and that s not necessarily a bad trait  wouldn t distinguish between the added conditions  they d start with select   from t where 1 1 and just add AND clauses after that   select   from t where 1 1 and name    Bob  and salary  gt  20000

User · Answer

Just adding a example code to Greg s answer   dim sqlstmt as new StringBuilder sqlstmt add  SELECT   FROM Products   sqlstmt add   WHERE 1 1          From now on you don t have to worry if you must       append AND or WHERE because you know the WHERE is there If ProductCategoryID  lt  gt  0 then   sqlstmt AppendFormat   AND ProductCategoryID    0    trim ProductCategoryID   end if If MinimunPrice  gt  0 then   sqlstmt AppendFormat   AND Price  gt    0    trim MinimunPrice   end if

User · Answer

I ve seen it used when the number of conditions can be variable    You can concatenate conditions using an   AND   string  Then  instead of counting the number of conditions you re passing in  you place a  WHERE 1 1  at the end of your stock SQL statement and throw on the concatenated conditions   Basically  it saves you having to do a test for conditions and then add a  WHERE  string before them

User · Answer

Indirectly Relevant  when 1 2 is used   CREATE TABLE New table name  as  select    FROM Old table name  WHERE 1   2    this will create a new table with same schema as old table   Very handy if you want to load some data for compares

User · Answer

While I can see that 1 1 would be useful for generated SQL  a technique I use in PHP is to create an array of clauses and then do  implode    AND     clauses     thus avoiding the problem of having a leading or trailing AND  Obviously this is only useful if you know that you are going to have at least one clause

User · Answer

Here s a closely related example  using a SQL MERGE statement to update the target tabled using all values from the source table where there is no common attribute on which to join on e g    MERGE INTO Circles    USING                  SELECT pi          FROM Constants         AS SourceTable    ON 1   1 WHEN MATCHED THEN    UPDATE      SET circumference   2   SourceTable pi   radius

User · Answer

Just adding a example code to Greg s answer   dim sqlstmt as new StringBuilder sqlstmt add  SELECT   FROM Products   sqlstmt add   WHERE 1 1          From now on you don t have to worry if you must       append AND or WHERE because you know the WHERE is there If ProductCategoryID  lt  gt  0 then   sqlstmt AppendFormat   AND ProductCategoryID    0    trim ProductCategoryID   end if If MinimunPrice  gt  0 then   sqlstmt AppendFormat   AND Price  gt    0    trim MinimunPrice   end if

[sql] Why would someone use WHERE 1=1 AND <conditions> in a SQL clause?

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