DROP ENCRYPT RULE 语法用于删除加密规则
DropEncryptRule ::=
'DROP' 'ENCRYPT' 'RULE' ifExists? encryptRuleName (',' encryptRuleName)*
ifExists ::=
'IF' 'EXISTS'
encryptRuleName ::=
identifier
ifExists 子句用于避免 Encrypt rule not exists 错误。DROP ENCRYPT RULE t_encrypt, t_encrypt_2;
ifExists 删除加密规则DROP ENCRYPT RULE IF EXISTS t_encrypt, t_encrypt_2;
DROP, ENCRYPT, RULE
