修改字段null为空字符串
UPDATE zxt_user_exam
SET type = ( CASE WHEN IFNULL( type, '' ) = '' THEN '' ELSE type END )
WHERE
type IS NULL
修改字段null为空字符串
UPDATE zxt_user_exam
SET type = ( CASE WHEN IFNULL( type, '' ) = '' THEN '' ELSE type END )
WHERE
type IS NULL