38 lines
		
	
	
		
			999 B
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			38 lines
		
	
	
		
			999 B
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
| --disable_query_log
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| set @@session.explicit_defaults_for_timestamp=off;
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| --enable_query_log
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| # owner: peihan.dph
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| # owner group: SQL1
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| # description
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| #
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| --disable_warnings
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| drop table if exists t1,t2,t5,t6;
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| --enable_warnings
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| #
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| ##
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| ## bug http://bugfree.corp.taobao.com/bug/199785
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| ## join with null values
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| ##
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| CREATE TABLE t1 (
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|   pk int primary key,
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|   id int,
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|   gender varchar(1)
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| );
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| CREATE TABLE t2 (
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|   user_id int primary key,
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|   birthday datetime
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| );
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| 
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| insert into t1 values (1, NULL, 'M'), (2, 1, 'M'), (3, 2, 'F'),(4, 3, 'F'),(5, 4, 'F'),(6, 5, 'M');
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| insert into t2 values (1, '2002-06-09 00:00:00'),(2, '2002-06-09 00:00:00'),(100, '2002-06-09 00:00:00'),
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| (3, '2002-06-09 00:00:00'),(4, '2002-06-09 00:00:00');
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| 
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| select  id,gender,user_id from  t1,t2  where t2.user_id=t1.id;
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| ####test for null safe equal with join....
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| create table t5(a int);
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| create table t6(a int);
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| insert into t5 values (null), (null);
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| insert into t6 values (null), (null);
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| select * from t5, t6 where t5.a <=> t6.a;
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| drop table t1,t2,t5,t6;
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