WHERE 1在MySQL查询中的重要性 [英] Importance of WHERE 1 in MySQL queries

问题描述

进行没有WHERE约束的MySQL查询时，大多数人在查询中使用WHERE 1.但是，省略WHERE 1不会影响查询.两者之间有区别吗?被认为是最佳实践吗?

When making a MySQL query with no WHERE constraints, most people use WHERE 1 in the query. However, omitting WHERE 1 does not influence the query. Is there a difference between the two? Is one considered to be the best practice?

推荐答案

我认为这不是最佳实践，但是人们有时会使用它来简化动态查询的构建.

I don't think it's a matter of best practice, but people sometimes use it to make building dynamic queries a bit easier.

string sql = "SELECT * FROM mytable WHERE 1 ";
if ( somecondition ) {
   sql += "AND somefield = somevalue ";
}

if ( someothercondition ) {
   sql += "AND someotherfield = someothervalue ";
}

... etc

如果没有WHERE 1，我需要检查每个if块是否需要放入WHERE或AND.

Without the WHERE 1 in there I would need to check in each if block whether I needed to put in a WHERE or an AND.

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