[英]SQL Different query depending on the if result
I want to do a query that depending on the char_length of one parameter should select one table or another. 我想执行一个查询,该查询取决于一个参数的char_length应该选择一个表还是另一个表。 It should be something like this but I know that is not correct at all and there are syntax errors which I can't find.
应该是这样的,但是我知道那根本不正确,而且我找不到语法错误。
SELECT IF (
CHAR_LENGTH('var44') < 3,
name FROM nets WHERE code = 'var44',
name FROM variable WHERE id = (SELECT SUBSTRING('var44',4))
);
Any ideas? 有任何想法吗? Thanks.
谢谢。
Would that be a solution for you: 这将为您提供解决方案:
select name from nets WHERE code = 'var44' and CHAR_LENGTH('var44') < 3
union
select name FROM variable WHERE id = (SELECT SUBSTRING('var44',4)) and CHAR_LENGTH('var44') >= 3
or is the if
statement forced? 还是
if
语句是强制的?
As GhostGambler said, why not do this with php? 正如GhostGambler所说,为什么不使用php?
if (strlen($var44)<3) {
$sql = mysql_query("SELECT name FROM nets WHERE code = '$var44'");
} else {
$var44 = substring($var44, 4);
$sql = mysql_query("SELECT name FROM variable WHERE id = '$var44'");
}
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