#Mysql count rows in all tables drivers
#Mysql count rows in all tables code

# Fetch each row manually and do our own count My $sql = 'SELECT usedby FROM depend WHERE usedby='Depend::Module' +AND uses='DBI'' My $sql = 'SELECT uses FROM depend WHERE usedby='Depend::Module' AN +D uses='DBI'' My $sql = 'SELECT * FROM depend WHERE usedby='Depend::Module'' My $sql = 'SELECT uses FROM depend WHERE usedby='Depend::Module'' # Doesn't count second field in this routine #use strict # because of the sub references This would propagate back through the do() result.

#Mysql count rows in all tables drivers

To suggest that some drivers return -1 untill all rows are fetched. Not sure whether the do() is portable.I was less interested in the fact that some of the tests returned the 'wrong' result than the time taken, clearly in aįull solution you need the correct answer :-).I don't know if there are any internal optimisations happening (i.e.The DB was small enough to fit in memory, and machine had no load, no no disk accesses during tests.(Tried - was quicker, but again, not DB pure) Store 'uses' relationship as a joined string in the module table and use PERLto manage.

(Not tried - Likely to be quicker, but less 'pure' and some complexity in forward references.)

#Mysql count rows in all tables code

be quicker, but at the expense of more lookup code and complication.)

Store IDs, rather than names in the DB.

In particular, I thought thatĭo() was just a wrapper round prepare/execute, so the time difference is

SELECT col1 is slightly faster than SELECT *.

Doesn't matter which column SELECT returns to do counting.

do() is more than twice as fast as prepare()/execute().

using WHERE A='X' AND B='Y' is faster than WHERE A='X'.

In this article you learned about different ways to get the number of rows of one or more tables in a MySQL database. To avoid this, you must follow the ANALYZE TABLE instruction before requesting the number of rows in the information_schema database.

This method is sometimes not accurate because the number of rows in information_schema and the actual number of rows in tables are not synchronized. Third, you execute the operator using the prepared operator as follows:ĭEALLOCATE PREPARE s Getting the number of MySQL rows of all tables in a database by one queryĪ quick way to get the number of rows of all tables in the database is to query data from the information_schema database directly: GROUP_CONCAT(CONCAT('SELECT '',table_name,' table_name,COUNT(*) rows FROM ',table_name) SEPARATOR ' UNION '), If you use MySQL 8.0+, you can use MySQL CTE (generic table expression) instead of a derived table: The next query uses the first query as a derived table and returns the SQL instruction as a string.ĪND table_type = 'BASE TABLE') table_list INTO query contains a list of table_list table names, which is the result of the query at the first stage. Second, to build the SQL operator, we use GROUP_CONCAT and CONCAT functions as follows: Third, execute a SQL statement using the prepared statementįirst, to get all the names of the database tables, you query the following from the information_schema database:.Second, create a SQL statement that includes all SELECT COUNT(*) FROM table_name operators for all tables separated by UNION.First, get all table names in the database.To get the number of rows of all tables in a particular database, such as classicmodels, you use the following steps:

To get the number of rows in several tables, you use the UNION operator to combine sets of results returned by each individual SELECT operator.įor example, to get the number of rows in a table and the number of rows in a single query, use the following instructions.Ģ rows in set (0.01 sec) Getting the number of MySQL rows of all tables in a particular database To get the number of rows per table, you use the COUNT(*) operator in SELECT as follows:įor example, to get the number of rows in the andreyex table in a database example, use the following operator:ġ row in set (0.01 sec) Getting the number of MySQL rows in two or more tables Getting the number of MySQL rows in one table Getting the number of MySQL rows of all tables in a database by one query