insert时带有where条件的写法

普通的insert into插入：

insert into T_SYNC_TABLE (id, entity_id, resource_id, create_date)
values (1, 1, 1, sysdate);

如果想要保证不插入重复记录，在插入时根据某字段判断，如果字段值已经存在，则不插入，否则插入。可以使用INSERT INTO IF EXISTS语法。

INSERT INTO table(field1, field2, fieldn) SELECT 'field1', 'field2', 'fieldn' FROM DUAL WHERE NOT EXISTS(SELECT field FROM table WHERE field = ?);

示例：

INSERT INTO T_SYNC_TABLE
(ID, ENTITY_ID, RESOURCE_ID, CREATE_DATE)
SELECT 1, 1, 1,SYSDATE FROM DUAL
WHERE NOT EXISTS
(SELECT * FROM T_SERVICE_MAINBODY WHERE CORPNAME = 'bbbb'
AND CID = (SELECT ID FROM T_KEY_CUSTOMER WHERE CUSTOMERNAME = 'aaaa')
);