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Source: ju. Outofmemory. Cn/entry / 336774

Several times recently, some developers asked me on Dingding, such as the picture below:

Update a record in MySQL, the syntax is correct, but the record is not updated…

When I first encountered this problem, I took this statement and directly executed it in the test library. I found that there was a problem, but there was still a difference with the development description. Here I use the test data to simulate:

SQL statement with problem:

The record before execution looks like this:

The record after execution looks like this:

As you can see, the result is not “as if it didn’t work”, but actually it does:

why?

MySQL > update MySQL > update MySQL > update MySQL

The format of assignment_list is a comma-separated list of col_name=value.

Go back and try again:

Sure enough, I got the result I wanted!

Summary: If you want to UPDATE multiple fields in an UPDATE statement, do not use “AND” between the fields. Instead, separate the fields with commas.

Owner_code =0; owner_code=0; After many attempts:

Is equivalent to:

(‘43212′ and owner_name=’ li si ‘) is a logical expression, and it is not obvious that owner_name is not ‘Li Si’.

Therefore, the result of this logical expression is false, which in MySQL is equivalent to 0!

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