删除临时变量
描述
DROP TEMPORARY VARIABLE 语句用于删除临时变量。如果该变量不存在，则会抛出异常。
语法
DROP TEMPORARY { VAR | VARIABLE } [ IF EXISTS ] variable_name
参数
-
变量名
指定现有变量的名称。该变量名可以可选地通过
system.session或session进行限定。语法:
[ system. [ session.] ] variable_name -
IF EXISTS
如果指定，则当变量不存在时不会抛出异常。
示例
-- Create a temporary variable var1
DECLARE VARIABLE var1 INT;
-- Drop temporary variable
DROP TEMPORARY VARIABLE var1;
-- Try to drop temporary variable which is not present
DROP TEMPORARY VARIABLE var1;
[VARIABLE_NOT_FOUND] The variable `system`.`session`.`var1` cannot be found. Verify the spelling and correctness of the schema and catalog.
If you did not qualify the name with a schema and catalog, verify the current_schema() output, or qualify the name with the correct schema and catalog.
To tolerate the error on drop use DROP VARIABLE IF EXISTS. SQLSTATE: 42883
-- Drop temporary variable if it exists
DROP TEMPORARY VARIABLE IF EXISTS var1;