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MySQLi Articles
Page 302 of 341
MySQL - How to count all rows per table in one query?
You can count all rows per table with the help of aggregate function count (TABLE_ROWS) from informatio_schema.tables. The syntax is as follows −SELECT table_name, TABLE_ROWS FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'yourDatabaseName';Now you can apply the above syntax to get all rows per table. The query is as follows −mysql> SELECT table_name, TABLE_ROWS FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'business';Here is the output −+------------------------------------------------------------------+------------+ | TABLE_NAME | TABLE_ROWS | +------------------------------------------------------------------+------------+ | accentsearchdemo ...
Read MoreGet the fields in each constraint in MySQL
Let’s say we have a database “business” with number of tables. If you want to Get the fields in each constraint, then use the below query.The below query is to get the fields in each one of those constraints −mysql> select * −> from information_schema.key_column_usage −> where constraint_schema = 'business';The following is the output −+--------------------+-------------------+--------------------------+---------------+--------------+------------------------------+--------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+ | CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | ORDINAL_POSITION | POSITION_IN_UNIQUE_CONSTRAINT | REFERENCED_TABLE_SCHEMA | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME | +--------------------+-------------------+--------------------------+---------------+--------------+------------------------------+--------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+ | def ...
Read MoreList of non-empty tables in all your MySQL databases?
To list non-empty tables in MySQL database, use “information_schema.tables”. The following is the query for all database tables −mysql> select table_type, table_name from information_schema.tables −> where table_rows >= 1;Above, we have considered only the table that have 1 or more than 1 rows i.e. non-empty table.The following is the output −+------------+------------------------------------------------------+ | TABLE_TYPE | TABLE_NAME | +------------+------------------------------------------------------+ | BASE TABLE | innodb_table_stats ...
Read MoreDisplay all tables inside a MySQL database using Java?
We will see here how to display all tables inside a MySQL database using Java. You can use show command from MySQL to get all tables inside a MySQL database.Let’s say our database is ‘test’. The Java code is as follows to show all table names inside a database ‘test’.The Java code is as follows. Here, connection is established between MySQL and Java −import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import com.mysql.jdbc.Connection; import com.mysql.jdbc.DatabaseMetaData; public class GetAllTables { public static void main(String[] args) throws SQLException { Connection conn = null; try { ...
Read MoreSelect last 20 records ordered in ascending order in MySQL?
To select last 20 records in ascending order, you can use subquery LIMIT clause. The syntax is as followsSELECT *FROM ( SELECT *FROM yourTableName ORDER BY yourColumnName desc limit 20 ) anyVariableName order by anyVariableName.yourColumnName;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table ProductInformation -> ( -> ProductId int, -> ProductName varchar(100), -> ProductPrice int -> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command. The query is as followsmysql> insert into ProductInformation values(101, 'Product-1', ...
Read MoreHow to Auto Generate Database Diagram in MySQL?
To auto generate database diagram in MySQL, use MySQL workbench. For this, select the option from database as shown below −Database->Reverse EngineerHere is the snapshot showing the Database tab −After clicking “Database” above, choose the option “Reverse Engineer”. This state the “Reverse Engineer” mode.Clicking above will display the following table automatically. We had one table in the database “business”. The same table “tblstudent” is visible here −
Read MoreHow can we use nested transactions in MySQL?
We can work with nested transactions in MySQL with the help of SAVEPOINT.Firstly, create a table. After that, begin the transaction.Now, insert records in the table created above. Use SAVEPOINT statement to set a named transaction savepoint with a name of identifier.Here are all the steps shown in the form of query −Create tablemysql> create table NestedTransactionDemo -> ( -> Name varchar(200) -> ); Query OK, 0 rows affected (0.63 sec)Start the transaction −mysql> START TRANSACTION; Query OK, 0 rows affected (0.00 sec)Now, insert a record in the tablemysql> insert into ...
Read MoreHow can I merge two MySQL tables?
To merge two MySQL tables, use the following syntax −INSERT IGNORE INTO yourTableName1 select *from yourTableName2;We will create two tables with some records. After that the merge process will begin using the above syntax.Creating first table −mysql> create table MergeDemo1 -> ( -> id int, -> primary key(id), -> Name varchar(200) -> ); Query OK, 0 rows affected (1.00 sec)Inserting records into the table −mysql> insert into MergeDemo1 values(1, 'John'); Query OK, 1 row affected (0.21 sec)Displaying records from the tablemysql> select *from MergeDemo1;The following ...
Read MoreHow to conduct an Accent Sensitive search in MySQL?
To conduct an Accent sensitive search in MySQL, we can use collation with utf8_bin. Here is the syntax to conduct accent sensitive search −yourColumName dataType collate utf8_bin;Apply the above syntax to conduct accent sensitive search. First, let us create a table −mysql> create table AccentSearchDemo -> ( -> Id varchar(100) collate utf8_bin -> ); Query OK, 0 rows affected (0.51 sec)Inserting three records into the table −mysql> insert into AccentSearchDemo values('John123'); Query OK, 1 row affected (0.31 sec) mysql> insert into AccentSearchDemo values('Smith123'); Query OK, 1 row affected (0.15 sec) mysql> ...
Read MoreHow to find the MySQL data directory from command line in Windows?
To find the MySQL data directory, we can simply use the variable datadir. Let us see how to use the variable with select statement.The query is as follows −mysql> select @@datadir;Here is the output+---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ 1 row in set (0.00 sec)Now we can reach the directory from the above sample output.Here is the snapshot that displays the MySQL data directory.
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