我遇到了放置运算符的sql查询<=>
。<=> 运算符是什么意思?
SELECT STR_ID, TEX_TEXT AS STR_DES_TEXT, IF( EXISTS( SELECT * FROM SEARCH_TREE AS SEARCH_TREE2 WHERE SEARCH_TREE2.STR_ID_PARENT <=> SEARCH_TREE.STR_ID LIMIT 1 ), 1, 0) AS DESCENDANTS FROM SEARCH_TREE
该 sql 是 MySQL 类型的。