什么是占位符

When you prepare a SQL statement or PL/SQL block that contains input data to be supplied at run time, placeholders in the SQL statement or PL/SQL block mark where data must be supplied. For example, the following SQL statement contains five placeholders, indicated by the leading colons (e.g., :ename), that show where input data must be supplied by the program.

INSERT INTO emp VALUES
    (:empno, :ename, :job, :sal, :deptno)

You can use placeholders for input variables in any DELETE, INSERT, SELECT, or UPDATE statement, or PL/SQL block, in any position in the statement where you can use an expression or a literal value. In PL/SQL, placeholders can also be used for output variables.

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1 楼 不吃鱼的猫 2008-11-24  

占位符用于参数绑定的，你上面贴的那个sql中values里面冒号开头的都是placeholder，在你的程序里面，可以通过类似setParameter(placeholder,realValue)来赋值。