选择列MySQL的默认值 [英] Select default value of column MySQL

问题描述

我不会详细介绍. 我有Java程序正在数据库中创建表.问题是创建表时，其中一个字段会获得默认值.因此，当我向该字段添加元素时，我想选择默认值.现在，加载所有元素的ID为:

I will not go deep in details. I have Java program which is creating tables in Database. The thing is that when table is created one of the fields get default value. So when I am adding elements to this field I want to select default value. Now loading of all element's ID is:

SELECT distinct(codeKind) FROM [table_name];

我想成为这样的人

SELECT [default value of column codeKind] from [table_name];

我检查了许多其他类似问题的答案，但都没有问题.

I checked many of answer of other similiar questions but none of them is OK.

谢谢.

推荐答案

使用coalesce

select coalesce(codeKind,<def_value>)

或者您可以为表的创建DDL设置一个固定值，例如

Alternatively you can set a fixed value for table's creation DDL such as

create table my_table ( my_column default 0, col2 int .... )，如果在插入语句中将列值保留为空白，则该值将自动填充为零.

create table my_table ( my_column default 0, col2 int .... ) , if you leave the column value as blank in the insert statement, then the value is automatically populated as zero.

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