Found 4219 Articles for MySQLi

MySQL will automatically assign sequence numbers to the AUTO_INCREMENT column even if we insert NULL, 0 or No Value to the column in a table.Examplemysql> create table test123(id INT PRIMARY KEY NOT NULL AUTO_INCREMENT, Name Varchar(10)); Query OK, 0 rows affected (0.15 sec)The query above created a MySQL table named ‘test123’ with columns named ‘id’ and ‘Name’. The column ‘id’ is declared AUTO_INCREMENT. Now, if we insert ‘No Value’, ‘0’ or ‘NULL’ in the ‘Name’ column, MySQL will assign the sequence numbers to column ‘id’. It can be seen from the result queries below −mysql> Insert Into test123(Name) values(''), ('0'), ... Read More

MySQL defines NCHAR as a way to indicate that a CHAR column should use predefined character set. Utf8 is used by MySQL as its predefined character set.ExampleIn the example below, we are creating a table named ‘Student1’. In this table, we are declaring the data types of three columns with three different declaration styles which are rather equivalent of each other. It is all due to NCHAR.mysql> Create table Student1(Name Char(10) character set utf8, Address NATIONAL CHARACTER(10), FatherName NCHAR(10));    Query OK, 0 rows affected (0.25 sec)Now on checking the status of table, with the help of query below, we ... Read More

On specifying a CHARACTER SET binary attribute for a character string data type, MySQL creates that column as its subsequent binary string type. The conversions for CHAR, VARCHAR and BLOB data types take place as follows −CHAR would become BINARYVARCHAR would become VARBINARYTEXT would become BLOBThe above kind of conversion does not occur for ENUM and SET data type and they both are created as declared while creating the table.ExampleIn the example below we have created a table named ‘EMP’ with four columns all specified as CHARACTER SET binary as follows −mysql> Create table Emp(Name varchar(10) CHARACTER SET binary, Address ... Read More

With the help of the following MySQL query we can check the character sets of all the tables in a particular database −mysql> Select Column_name, TABLE_NAME, CHARACTER_SET_NAME FROM        INFORMATION_SCHEMA.Columns Where TABLE_SCHEMA = 'db_name';ExampleFor example, the query below returns the character sets of all the tables along with the column names in a database named ‘Alpha’.mysql> Select Column_name 'Column', TABLE_NAME, CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.Columns Where TABLE_SCHEMA = 'Alpha'; +---------+------------+--------------------+ | Column  | TABLE_NAME | CHARACTER_SET_NAME | +---------+------------+--------------------+ | Name    | employee   | latin1             | | email   | employee   ... Read More

With the help of the following MySQL query we can check the character sets of all the tables in a particular database −mysql> Select TABLE_NAME, CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.Columns Where TABLE_SCHEMA = 'db_name';ExampleFor example, the query below returns the character sets of all the tables in a database named ‘Alpha’.mysql> Select TABLE_NAME, CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.Columns Where TABLE_SCHEMA = 'Alpha'; +------------+--------------------+ | TABLE_NAME | CHARACTER_SET_NAME | +------------+--------------------+ | employee   | latin1             | | employee   | latin1             | | student    | latin1             ... Read More

We can use DELETE statement along with a WHERE clause, which identifies those multiple rows, to delete multiple rows from MySQL table.Examplemysql> Select * from names; +------+-----------+ | id   | name      | +------+-----------+ | 1    | Rahul     | | 2    | Gaurav    | | 3    | Raman     | | 5    | Ram       | +------+-----------+ 4 rows in set (0.00 sec) mysql> DELETE from names WHERE id > 2; Query OK, 2 rows affected (0.04 sec)The query above will delete multiple rows because WHERE clause identify two rows having id > 2 from table ‘names’.mysql> Select * from names; +------+-----------+ | id   | name      | +------+-----------+ | 1    | Rahul     | | 2    | Gaurav    | +------+-----------+ 2 rows in set (0.00 sec)

Following is the query to check character set of the columns of MySQL table −mysql> Select Column_name 'Column', Character_set_name 'Charset' FROM        information_schema.columns where table_schema = 'db_name' and        table_name ='table_name';ExampleFor example, the query below returns the name of the columns of ‘test_char_set’ table in a database named ‘sample’ along with the character sets of those columns.mysql> Select Column_name 'Column', Character_set_name 'Charset' FROM        information_schema.columns where table_schema = 'Sample' and        table_name ='test_char_set'; +--------+---------+ | Column | Charset | +--------+---------+ | Name   | latin1  | | Field  | latin1  | ... Read More

Following is the query to check default character set of the particular MySQL database −mysql> SELECT SCHEMA_NAME 'DatabaseName', default_character_set_name 'Charset' FROM information_schema.SCHEMATA where schema_name = 'db_name';ExampleFor example, the query below will return the default character set of a database named ‘Sample’ −mysql> SELECT SCHEMA_NAME 'DatabaseName', default_character_set_name 'Charset' FROM information_schema.SCHEMATA where schema_name = 'Sample'; +----------------+---------+ | DatabaseName   | Charset | +----------------+---------+ | Sample         | latin1  | +----------------+---------+ 1 row in set (0.00 sec)

The query below will return the name of the database along with the default character set −mysql> SELECT SCHEMA_NAME 'Database', default_character_set_name 'charset' FROM information_schema.SCHEMATA; +--------------------+---------+ | Database           | Charset | +--------------------+---------+ | information_schema | utf8    | | gaurav             | latin1  | | menagerie          | latin1  | | mysql              | latin1  | | performance_schema | utf8    | | sample             | latin1  | | test               | latin1  | | tutorial           | latin1  | +--------------------+---------+ 8 rows in set (0.00 sec)

We can use DELETE statement along with a WHERE clause, which identifies that particular row, to delete a row from MySQL table.Examplemysql> Select * from names; +------+-----------+ | id   | name      | +------+-----------+ | 1    | Rahul     | | 2    | Gaurav    | | 3    | Raman     | | 4    | Aarav     | | 5    | Ram       | +------+-----------+ 5 rows in set (0.00 sec) mysql> DELETE from names where id = 4; Query OK, 1 row affected (0.07 sec)The query above will delete a single row having id = 4 from table ‘names’.mysql> Select * from names; +------+-----------+ | id   | name      | +------+-----------+ | 1    | Rahul     | | 2    | Gaurav    | | 3    | Raman     | | 5    | Ram       | +------+-----------+ 4 rows in set (0.00 sec)