A small example of Row_count () in Mysql _mysql

Note: the Row_count () in MySQL can return the number of rows affected by the previous SQL Update,delete,insert operation.

Test on MySQL (database version: 5.1.22):

1. Create a database table:

Copy Code code as follows:

CREATE TABLE T (
ID int,
Name varchar (50),
Address varchar (100),
Primary KEY (Id,name)
) engine =innodb;

2. Insert test data:

Copy Code code as follows:

INSERT INTO T
(id,name,address)
Values
(1, ' Yubowei ', ' Weifang '),
(2, ' Sam ', ' Qingdao ');

3. Update:

Copy Code code as follows:

Update T set address = ' Weifang '
where id = 1 and name = ' Yubowei ';

View the number of rows affected at this time:
Select Row_count (); ==〉 execution result is 0;

4. Re-update:

Copy Code code as follows:

Update T set address = ' Beijing '
where id = 1 and name = ' Yubowei ';

View the number of rows affected at this time:
Select Row_count (); ==〉 execution result is 1;
From the above test can be found in MySQL only if the record is actually modified in the case, Row_count will not be able to record the number of rows affected, otherwise if the record exists but there is no actual modification will not record the update to Row_count.

Note:
Today, with prepare dynamic processing of the UPDATE statement, found that the Row_count () function returned to the 1, check the original is the Row_count () into the deallocate statement behind.
God-like me, made such a mistake, ha.