sql语句中 values值为什么要加单引号呢？values里面的放的本身就是PHP变量名字呀，双引号中可以解析变量值，为什么还要在变量中加单引号呢
Why do values in sql statements need to be enclosed in single quotes? -PHP Chinese website Q&A-Why should single quotes be added to the values in the sql statement? -PHP Chinese website Q&A
Please watch and learn.
sql = "insert into user(name, age, class) values('李四', 18, '高三一班')";
1 双引号中的是一个标准的SQL语句，把他拿到mysql中可以单独执行
2 因为是SQL语句，字符型的字段的值要用单引号括起来加以标注
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Why do values in sql statements need to be enclosed in single quotes? -PHP Chinese website Q&A-Why should single quotes be added to the values in the sql statement? -PHP Chinese website Q&A
Please watch and learn.
sql = "insert into user(name, age, class) values('李四', 18, '高三一班')";1 双引号中的是一个标准的SQL语句，把他拿到mysql中可以单独执行
2 因为是SQL语句，字符型的字段的值要用单引号括起来加以标注