MySQL those things (6) where conditional string quotes

Preface: The so-called pit, two meaning, one is the software itself bug, one is the user often make mistakes.

Phper often deals with MySQL in daily development. Especially in small and medium-sized applications without layering, phper development should focus on the implementation of SQL statements.

To the point, the table statement is built:

DROP TABLE IF EXISTS ' test_sql ';

CREATE TABLE ' Test_sql ' (

' id ' int (ten) unsigned not NULL auto_increment COMMENT ' self-increment id ',

' Name ' varchar (+) not NULL DEFAULT ' 0 ' COMMENT ' name ',

PRIMARY KEY (' id ')

) Engine=innodb auto_increment=1 DEFAULT charset=utf8 comment= ' Test form ';

Data on:

INSERT into ' test_sql '

VALUES

(' 1 ', ' 0 '),

(' 2 ', ' www.haodaquan.com '),

(' 3 ', ' 0 '),

(' 4 ', ' 123 '),

(' 5 ', ' 123php '),

(' 6 ', ' 123php on the Road '),

(' 7 ', ' PHP on the Road ');

Okay, here's the Watch:

Here's the question: Look for data with a name value of 0.

So the wrong SQL came out:

Select ' id ', ' name ' from Test_sql where name=0

The results are inconsistent with expectations, such as:

Why?

SQL is also a weak type, but it also returns true when comparing 0 and string.

The correct sql:

Select ' id ', ' name ' from Test_sql where name= ' 0 '

Conclusion: The field of a character type must be quoted when you make a where condition.

MySQL those things (6) where conditional string quotes