使用AND而不是COMMA时，UPDATE语句未生成语法错误 [英] UPDATE Statement not generating syntax error when using AND instead of COMMA

问题描述

我正在浏览有关更新的MySQL文档. 请参见UPDATE语法 .我发现语法是

I was browsing on MySQL Documentation about the update. See UPDATE Syntax. I found out that the syntax is

UPDATE [LOW_PRIORITY] [IGNORE] table_reference
    SET col_name1={expr1|DEFAULT} [, col_name2={expr2|DEFAULT}] ...
    [WHERE where_condition]
    [ORDER BY ...]
    [LIMIT row_count]

我执行此语句时

UPDATE SampleTB
SET NAME = '123' AND Address = '456'
WHERE ID = 1;

请参阅此处以获取SQL Fiddle演示链接

See Here for SQL Fiddle Demonstration Link

查询成功执行，Name的值为0.我期待查询出现语法错误.

The query executed successfully and the value of Name was 0. I was expecting a syntax error on the query.

有人可以向我解释为什么它没有产生错误吗?为什么该列的新值是zero而不是123?

Can somebody explain to me why it didn't generate an error? And why was the new value of the column is zero and not 123?

推荐答案

SET NAME = '123' AND Address = '456'

解析为以下内容:

SET NAME = ('123' AND (Address = '456'))

是一个字符串和布尔操作数的比较和布尔AND.

which is one comparison and boolean AND of a string and boolean operands.

因此它获取当前行的Address列值，将其与'456'字符串进行比较，并且比较结果用作AND的第二个操作数，如'123' AND false

So it takes the current row's Address column value, compares it to a '456' string and result of the comparison is used as a second operand for AND like '123' AND false

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