This function returns the number of rows changed by the previous SQL statement executed. If the previous statement was not one that could potentially change data rows—in other words, it wasn’t an Show SELECT ROW_COUNT(); +-------------+ | ROW_COUNT() | +-------------+ | 4 | +-------------+ The results here show that four rows were changed. Get MySQL in a Nutshell, 2nd Edition now with the O’Reilly learning platform. O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers. ROW_COUNT() returns a value as follows: For UPDATE statements, the affected-rows value by default is the number of rows actually changed.If you
specify the CLIENT_FOUND_ROWS flag to mysql_real_connect() when connection to mysqld, the affected-rows value is the number of rows "found"; that is, matched by the WHERE clause. For REPLACE statements, the affected-rows value is 2 if the new row replaced an old row, because in this case, one row was inserted after the duplicate was delete. For The ROW_COUNT() value is similar to the value from the mysql_affected\rows() C API function and the row count that the mysql client displays following statement
execution. Important ROW_COUNT() is not replicated reliably using statement-based replication. This function is automatically replicated using row-based replication. results matching ""No results matching ""mysql> mysql> mysql> CREATE TABLE t (id INT NOT NULL); Query OK, 0 rows affected (0.01 sec) mysql> mysql> INSERT INTO t VALUES(1), -> (2), -> (3); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> mysql> SELECT ROW_COUNT(); +-------------+ | ROW_COUNT() | +-------------+ | 3 | +-------------+ 1 row in set (0.00 sec) mysql> mysql> DELETE FROM t WHERE id IN(1,2); Query OK, 2 rows affected (0.00 sec) mysql> mysql> SELECT ROW_COUNT(); +-------------+ | ROW_COUNT() | +-------------+ | 2 | +-------------+ 1 row in set (0.02 sec) mysql> mysql> drop table t; Query OK, 0 rows affected (0.00 sec) mysql> mysql>
13.2.13 UPDATE Statement An Single-table syntax:
Multiple-table syntax:
For the single-table syntax, the For the multiple-table syntax,
For partitioned tables, both the single-single and multiple-table forms of this statement support the use of a Note Unlike the case when using For more information and examples, see Section 24.5, “Partition Selection”. You need the The
If you access a column from the table to be updated in an expression,
The second assignment in the following statement sets
Single-table If you set a column to the value it currently has, MySQL notices this and does not update it. If you update a column that has been declared If a generated column is updated explicitly, the only permitted value is
You can use If an
For example, if the table contains 1 and 2 in the
You can also perform
The
preceding example shows an inner join that uses the comma operator, but multiple-table If you use a multiple-table
You cannot update a table and select directly from the same table in a subquery. You can work around this by using a multi-table update in which one of the tables is derived from the table that you actually wish to update, and referring to the derived table using an alias. Suppose
you wish to update a table named
To reduce the retail price of any items for which the markup is 30% or greater and of which you have fewer than one hundred in stock, you might try to use an
Instead, you can employ a multi-table update in which the subquery is moved into the
list of tables to be updated, using an alias to reference it in the outermost
Because the optimizer tries by default to merge the derived table
The advantage of using the optimizer hint in such a case is that it applies only within
the query block where it is used, so that it is not necessary to change the value of Another possibility is to rewrite the subquery so that it does not use
In this case, the subquery is materialized by default rather than merged, so it is not necessary to disable merging of the derived table. What is Row_count () in MySQL?Description. ROW_COUNT() returns the number of rows updated, inserted or deleted by the preceding statement. This is the same as the row count that the mysql client displays and the value from the mysql_affected_rows() C API function.
How to get number of rows inserted IN MySQL?We can get the total number of rows in a table by using the MySQL mysqli_num_rows() function. Syntax: mysqli_num_rows( result ); The result is to specify the result set identifier returned by mysqli_query() function.
How can I see how many rows affected in MySQL?mysql_affected_rows() may be called immediately after executing a statement with mysql_real_query() or mysql_query() . It returns the number of rows changed, deleted, or inserted by the last statement if it was an UPDATE , DELETE , or INSERT . For SELECT statements, mysql_affected_rows() works like mysql_num_rows() .
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