sql_auto_is_null

Description

sql_auto_is_null is used by some special drivers, such as ODBC, to control whether to retrieve the value of the auto-increment column of the last inserted row.

Privilege requirements

• Query variables

  • Global level

    The sys tenant and all user tenants can use the SHOW VARIABLES statement or the SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE view (Oracle mode) and the information_schema.GLOBAL_VARIABLES view (MySQL mode) to view the value of a global system variable.

  • Session level

    The sys tenant and all user tenants can use the SHOW VARIABLES statement or the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view (Oracle mode) and the information_schema.SESSION_VARIABLES view (MySQL mode) to view the value of a session system variable.

• Modify variables

  • Global level

    • The sys tenant can directly modify the value of a global system variable.

    • MySQL user tenants must have the SUPER or ALTER SYSTEM privilege to modify the value of a global system variable.

    • Oracle user tenants must have the ALTER SYSTEM privilege to modify the value of a global system variable.

  • Session level

    The sys tenant and all user tenants can directly modify the value of a session system variable.

Attributes

Usage

Assume that a table named t1 exists. The statement for creating the table is as follows:

obclient> CREATE TABLE t1 (auto_inc_column auto_increment, j int);

When sql_auto_is_null is set to ON, the following two statements are equivalent:

obclient> SELECT * FROM t1 WHERE auto_inc_column is null;

obclient> SELECT * FROM t1 WHERE auto_inc_column = last_insert_id();

Examples

Set the value of sql_auto_is_null to ON so that you can directly query the value of the auto-increment column of the last inserted row by using the IS NULL condition.

• Session level

  obclient> SET sql_auto_is_null = on;
  

• Global level

  obclient> SET GLOBAL sql_auto_is_null = on;