使用用户定义的变量指定列别名 [英] Specifying column alias with user-defined variable

问题描述

我想使用用户定义的变量重命名查询的列.

I want to rename the columns of a query by using user-defined variables.

例如:

select id as @rt from table_name

推荐答案

这是不可能的.您必须动态创建 sql 字符串.

This is not possible. You would have to create the sql string dynamically.

C#:

string columnName = "xy";
string sql = "SELECT id AS " + columnName + " FROM table_name";

VB:

Dim columnName As String = "xy"
Dim sql As String = "SELECT id AS " & columnName & " FROM table_name"

您也可以在 MySql 的存储过程中执行此操作.有关预处理语句的 SQL 语法

You can also do that in a stored procedure with MySql. See MySql documentation for SQL Syntax for Prepared Statements

它看起来像这样(未经测试):

It would look something like this (not tested):

CREATE PROCEDURE myProc (columnName VARCHAR(30))
BEGIN
SET @sql = CONCAT("SELECT id AS ", columnName, " FROM table_name");
    PREPARE s1 FROM @sql;
    EXECUTE s1;
    DEALLOCATE PREPARE s1;
END$$

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