What is the PostgreSQL equivalent for ISNULL

Question

In MS SQL-Server  I can do   SELECT ISNULL Field  Empty   from Table  But in PostgreSQL I get a syntax error  How do I emulate the ISNULL   functionality

User · Accepted Answer

SELECT CASE WHEN field IS NULL THEN  Empty  ELSE field END AS field alias   Or more idiomatic   SELECT coalesce field   Empty   AS field alias

User · Answer

How do I emulate the ISNULL   functionality     SELECT  Field IS NULL  FROM

User · Answer

Create the following function  CREATE OR REPLACE FUNCTION isnull text  text  RETURNS text AS  SELECT  CASE  SELECT  1        is null  WHEN true THEN  2 ELSE  1 END  AS RESULT  LANGUAGE  sql    And it ll work   You may to create different versions with different parameter types

User · Answer

Use COALESCE   instead    SELECT COALESCE Field  Empty   from Table    It functions much like ISNULL  although provides more functionality  Coalesce will return the first non null value in the list  Thus   SELECT COALESCE null  null  5      returns 5  while  SELECT COALESCE null  2  5     returns 2  Coalesce will take a large number of arguments  There is no documented maximum  I tested it will 100 arguments and it succeeded  This should be plenty for the vast majority of situations

User · Answer

Try   SELECT COALESCE NULLIF field       another field  FROM table name

[sql-server] What is the PostgreSQL equivalent for ISNULL()

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