mysql 5.0/5.1 questions for learning purposes

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table1 was created like this:

create table table1 (id int primary key,name varchar(32));
insert into table1 values (1,'a'),(2,'b'),(3,'zeh');

a) delete from table1 where id+1=10;
b) update table1 v1 set v1.name='v'
     where abs(id)=12;
c) update table1 v1 set v1.name='v' where id
     between 1 and 999999 and name='f';

One Response

1. urs — 5. February 2010 @ 00:34:38 —

   
   Answers:

   a b

   When a function is used on a column, its corresponding index cannot be used.
   c works, because the index on id can be used.

   mysql> delete from table1 where id+1=10;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column

   mysql> update table1 v1 set v1.name='v' where abs(id)=12;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
   

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