I need to query the database to get the column names, not to be confused with data in the table. For example, if I have a table named EVENT_LOG that contains eventID, eventType, eventDesc, and eventTime, then I would want to retrieve those field names from the query and nothing else.
I found how to do this in:
But I need to know: how can this be done in Oracle?
In SQL Server...
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = (SELECT id FROM sysobjects WHERE type = 'V' AND [Name] = 'Your table name')
Type = 'V' for views Type = 'U' for tables
The answer is here: http://php.net/manual/en/function.mysql-list-fields.php I'd use the following code in your case:
$result = mysql_query("SHOW COLUMNS FROM sometable");
if (!$result) {
echo 'Could not run query: ' . mysql_error();
exit;
}
$fields = array();
if (mysql_num_rows($result) > 0) {
while ($row = mysql_fetch_assoc($result)) {
$fields[] = $row['Field'];
}
}
Came across this question looking for access to column names on Teradata, so I'll add the answer for their 'flavour' of SQL:
SELECT ColumnName
FROM DBC.Columns
WHERE DatabaseName='DBASE_NAME'
AND TableName='TABLE_NAME';
The info is stored in the DBC dbase.
Getting data types is a little bit more involved: Get column type using teradata system tables
SELECT COLUMN_NAME 'all_columns'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME='user';
SELECT COLUMN_NAME
FROM YourDatabase.INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'YourTableName'
For SQL Server 2008, we can use information_schema.columns for getting column information
SELECT *
FROM information_schema.columns
WHERE table_name = 'Table_Name'
ORDER BY ordinal_position
For SQL Server:
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = object_id('TABLE_NAME')
SELECT A.COLUMN_NAME, A.* FROM all_tab_columns a
WHERE table_name = 'Your Table Name'
AND A.COLUMN_NAME = 'COLUMN NAME' AND a.owner = 'Schema'
That information is stored in the ALL_TAB_COLUMNS system table:
SQL> select column_name from all_tab_columns where table_name = 'DUAL';
DUMMY
Or you could DESCRIBE the table if you are using SQL*PLUS:
SQL> desc dual
Name Null? Type
----------------------------------------------------- -------- ---------------------- -------------
DUMMY VARCHAR2(1)
For Oracle
SELECT column_name FROM user_tab_cols WHERE table_name=UPPER('tableName');
For SQL Server 2008, we can use information_schema.columns for getting column information
SELECT *
FROM information_schema.columns
WHERE table_name = 'Table_Name'
ORDER BY ordinal_position
Try this
select * from sys.all_columns c join sys.objects o on c.object_id=o.object_id where o.name = 'TABLENAME' and c.name like '%COLUMN NAME%'
For SQLite I believe you can use something like the following:
PRAGMA table_info(table-name);
Explanation from sqlite.org:
This pragma returns one row for each column in the named table. Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column. The "pk" column in the result set is zero for columns that are not part of the primary key, and is the index of the column in the primary key for columns that are part of the primary key.
See also: Sqlite.org Pragma Table Info
Even this is also one of the way we can use it
select * from product where 1 != 1
For Oracle
SELECT column_name FROM user_tab_cols WHERE table_name=UPPER('tableName');
you can run this query
SELECT t.name AS table_name,
SCHEMA_NAME(schema_id) AS schema_name,
c.name AS column_name
FROM sys.tables AS t
INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID
WHERE c.name LIKE '%%' --if you want to find specific column write here
ORDER BY schema_name, table_name;
SELECT COLUMN_NAME 'all_columns'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME='user';
You can do this:
describe EVENT_LOG
or
desc EVENT_LOG
Note: only applicable if you know the table name and specifically for Oracle.
You could also try this, but it might be more information than you need:
sp_columns TABLE_NAME
You can do this:
describe EVENT_LOG
or
desc EVENT_LOG
Note: only applicable if you know the table name and specifically for Oracle.
Mysql
SHOW COLUMNS FROM a_table_named_users WHERE Field REGEXP 'user_id|user_name|user_pass'
This will return a result something like this:
Field | Type | Null | Key | Default | Extra
user_id int(8) NO PRI NULL auto_increment
user_name varchar(64) NO MUL NULL
user_pass varchar(64) NO NULL
Then to pull out the values you can simply
fetch row[0]
This is also great for passing input dynamically since the REGEXP needs the '|' for multiple inputs, but is also a way to keeps data separated and easy to store/pass to classes/functions.
Try throwing in dummy data as well for security when sending it out and compare what was returned when receiving any errors.
The other answers sufficiently answer the question, but I thought I would share some additional information. Others describe the "DESCRIBE table" syntax in order to get the table information. If you want to get the information in the same format, but without using DESCRIBE, you could do:
SELECT column_name as COLUMN_NAME, nullable || ' ' as BE_NULL,
SUBSTR(data_type || '(' || data_length || ')', 0, 10) as TYPE
FROM all_tab_columns WHERE table_name = 'TABLENAME';
Probably doesn't matter much, but I wrote it up earlier and it seems to fit.
For MySQL, use
SELECT column_name
FROM information_schema.columns
WHERE
table_schema = 'Schema' AND table_name = 'Table_Name'
The other answers sufficiently answer the question, but I thought I would share some additional information. Others describe the "DESCRIBE table" syntax in order to get the table information. If you want to get the information in the same format, but without using DESCRIBE, you could do:
SELECT column_name as COLUMN_NAME, nullable || ' ' as BE_NULL,
SUBSTR(data_type || '(' || data_length || ')', 0, 10) as TYPE
FROM all_tab_columns WHERE table_name = 'TABLENAME';
Probably doesn't matter much, but I wrote it up earlier and it seems to fit.
Just select first row from the table , for oracle : select * from <table name> where rownum = 1;
For MySQL, use
SELECT column_name
FROM information_schema.columns
WHERE
table_schema = 'Schema' AND table_name = 'Table_Name'
SELECT COLUMN_NAME
FROM YourDatabase.INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'YourTableName'
The other answers sufficiently answer the question, but I thought I would share some additional information. Others describe the "DESCRIBE table" syntax in order to get the table information. If you want to get the information in the same format, but without using DESCRIBE, you could do:
SELECT column_name as COLUMN_NAME, nullable || ' ' as BE_NULL,
SUBSTR(data_type || '(' || data_length || ')', 0, 10) as TYPE
FROM all_tab_columns WHERE table_name = 'TABLENAME';
Probably doesn't matter much, but I wrote it up earlier and it seems to fit.
describe YOUR_TABLE;
In your case :
describe EVENT_LOG;
That information is stored in the ALL_TAB_COLUMNS system table:
SQL> select column_name from all_tab_columns where table_name = 'DUAL';
DUMMY
Or you could DESCRIBE the table if you are using SQL*PLUS:
SQL> desc dual
Name Null? Type
----------------------------------------------------- -------- ---------------------- -------------
DUMMY VARCHAR2(1)
Even this is also one of the way we can use it
select * from product where 1 != 1
That information is stored in the ALL_TAB_COLUMNS system table:
SQL> select column_name from all_tab_columns where table_name = 'DUAL';
DUMMY
Or you could DESCRIBE the table if you are using SQL*PLUS:
SQL> desc dual
Name Null? Type
----------------------------------------------------- -------- ---------------------- -------------
DUMMY VARCHAR2(1)
In SQL Server...
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = (SELECT id FROM sysobjects WHERE type = 'V' AND [Name] = 'Your table name')
Type = 'V' for views Type = 'U' for tables
For SQLite I believe you can use something like the following:
PRAGMA table_info(table-name);
Explanation from sqlite.org:
This pragma returns one row for each column in the named table. Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column. The "pk" column in the result set is zero for columns that are not part of the primary key, and is the index of the column in the primary key for columns that are part of the primary key.
See also: Sqlite.org Pragma Table Info
Try this
select * from sys.all_columns c join sys.objects o on c.object_id=o.object_id where o.name = 'TABLENAME' and c.name like '%COLUMN NAME%'
In Oracle, there is two views that describe columns:
DBA_TAB_COLUMNS describes the columns of all tables, views, and clusters in the database.
USER_TAB_COLUMNS describes the columns of the tables, views, and
clusters owned by the current user. This view does not display the
OWNER column.
Came across this question looking for access to column names on Teradata, so I'll add the answer for their 'flavour' of SQL:
SELECT ColumnName
FROM DBC.Columns
WHERE DatabaseName='DBASE_NAME'
AND TableName='TABLE_NAME';
The info is stored in the DBC dbase.
Getting data types is a little bit more involved: Get column type using teradata system tables
In Oracle, there is two views that describe columns:
DBA_TAB_COLUMNS describes the columns of all tables, views, and clusters in the database.
USER_TAB_COLUMNS describes the columns of the tables, views, and
clusters owned by the current user. This view does not display the
OWNER column.
You can do this:
describe EVENT_LOG
or
desc EVENT_LOG
Note: only applicable if you know the table name and specifically for Oracle.
SELECT A.COLUMN_NAME, A.* FROM all_tab_columns a
WHERE table_name = 'Your Table Name'
AND A.COLUMN_NAME = 'COLUMN NAME' AND a.owner = 'Schema'
You can do this:
describe EVENT_LOG
or
desc EVENT_LOG
Note: only applicable if you know the table name and specifically for Oracle.
You could also try this, but it might be more information than you need:
sp_columns TABLE_NAME
In SQL Server...
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = (SELECT id FROM sysobjects WHERE type = 'V' AND [Name] = 'Your table name')
Type = 'V' for views Type = 'U' for tables
That information is stored in the ALL_TAB_COLUMNS system table:
SQL> select column_name from all_tab_columns where table_name = 'DUAL';
DUMMY
Or you could DESCRIBE the table if you are using SQL*PLUS:
SQL> desc dual
Name Null? Type
----------------------------------------------------- -------- ---------------------- -------------
DUMMY VARCHAR2(1)
describe YOUR_TABLE;
In your case :
describe EVENT_LOG;
The other answers sufficiently answer the question, but I thought I would share some additional information. Others describe the "DESCRIBE table" syntax in order to get the table information. If you want to get the information in the same format, but without using DESCRIBE, you could do:
SELECT column_name as COLUMN_NAME, nullable || ' ' as BE_NULL,
SUBSTR(data_type || '(' || data_length || ')', 0, 10) as TYPE
FROM all_tab_columns WHERE table_name = 'TABLENAME';
Probably doesn't matter much, but I wrote it up earlier and it seems to fit.
select column_name,* from information_schema.columns
where table_name = 'YourTableName'
order by ordinal_position
In SQL Server...
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = (SELECT id FROM sysobjects WHERE type = 'V' AND [Name] = 'Your table name')
Type = 'V' for views Type = 'U' for tables
For SQL Server:
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = object_id('TABLE_NAME')
select column_name,* from information_schema.columns
where table_name = 'YourTableName'
order by ordinal_position
you can run this query
SELECT t.name AS table_name,
SCHEMA_NAME(schema_id) AS schema_name,
c.name AS column_name
FROM sys.tables AS t
INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID
WHERE c.name LIKE '%%' --if you want to find specific column write here
ORDER BY schema_name, table_name;
I did it like this
SELECT
TOP 0
*
FROM
Posts
It works even in http://data.stackexchange.com whose service tables I am not aware of!
Mysql
SHOW COLUMNS FROM a_table_named_users WHERE Field REGEXP 'user_id|user_name|user_pass'
This will return a result something like this:
Field | Type | Null | Key | Default | Extra
user_id int(8) NO PRI NULL auto_increment
user_name varchar(64) NO MUL NULL
user_pass varchar(64) NO NULL
Then to pull out the values you can simply
fetch row[0]
This is also great for passing input dynamically since the REGEXP needs the '|' for multiple inputs, but is also a way to keeps data separated and easy to store/pass to classes/functions.
Try throwing in dummy data as well for security when sending it out and compare what was returned when receiving any errors.
Just select first row from the table , for oracle : select * from <table name> where rownum = 1;
Source: Stackoverflow.com