2018年2月11日15:34:23
做PHP开发时，要写一个SQL语句。就是如果表中存在相应的记录时，就执行更新，不存在就执行插入。
记得以前做SQL SERVER时，有merge into 语句，可以按查询条件，选择要执行的操作，是插件还是更新。但是mysql好像没这个功能。它是按主键是是否存在进行辨别的。
所以习惯性地写了如下语句：
INSERT INTO readbook (readid,readpage,readcount,bookid,userid,readtime) VALUES ( (SELECT readid From readbook where userid=1 and bookid=1 and readpage=5),5,1,1,1,now()) ON duplicate key UPDATE readcount=readcount + 1,readtime=now()
结果提示错误，如下：
静态分析： 分析时发现11个错误。 Unrecognized keyword. (near "key" at position 185) Unexpected token. (near "=" at position 209) Unexpected token. (near "readcount" at position 210) Unexpected token. (near "+" at position 220) Unexpected token. (near "1" at position 222) Unexpected token. (near "," at position 223) Unexpected token. (near "readtime" at position 224) Unexpected token. (near "=" at position 232) Unrecognized keyword. (near "now" at position 233) Unexpected token. (near "(" at position 236) Unexpected token. (near ")" at position 237) SQL 查询： 文档 INSERT INTO readbook (readid,readpage,readcount,bookid,userid,readtime) VALUES ( (SELECT readid From readbook where userid=1 and bookid=1 and readpage=5) ,5,1,1,1,now()) ON duplicate key UPDATE readcount=readcount + 1,readtime=now() MySQL 返回： 文档 #1093 - You can't specify target table 'readbook' for update in FROM clause