MySQL的準備報告問題

Question

我有以下簡單的表結構和事先準備好的聲明：

create table junk1(name varchar(10), state varchar(10)); 
create table junk2(state varchar(100)); 
insert into junk2(state)values("state like '%Tex%'"),("state like '%Neb%'"),("state like '%Was%'"); 
insert into junk1(name, state) values ('asa', 'Texas'), ('dff', 'Washing'), ('fgfgf', 'Oklahoma'), ('bbb', 'Nevada'), ('hhh', 'Texas'), ('jjj', 'Nebraska'); 
SET @va = ''; 
select group_concat(state separator ' OR ') into @va from junk2; 
PREPARE stmt1 FROM 'select * from junk1 where ?'; 
execute stmt1 using @va; 
deallocate prepare stmt1; 

我沒有得到的結果如預期。我沒有得到任何結果。我在這裏做錯了什麼？

Answer 1

您不能在預處理語句中使用語法元素作爲參數，即不能將整個where子句作爲參數傳遞，只能使用值。

你可能想連接您的where子句來代替：

select group_concat(state separator '" OR "') into @va from junk2; 
set @clause = concat('select * from junk1 where "', @va, '"'); 
PREPARE stmt1 FROM @clause;