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MySQLi Articles
Page 30 of 341
MySQL query to increment one of the column values
Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(100), -> Score int -> ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name, Score) values('John', 68); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable(Name, Score) values('Carol', 98); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable(Name, Score) values('David', 89); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(Name, Score) values('Robert', 67); Query OK, 1 row affected ...
Read MoreGiven a column name how can I find which tables in a MySQL database contain that column?
Use the COLUMN_NAME to find which table in a database contains a specific column. Let us first create a table −mysql> create table DemoTable -> ( -> CustomerId int, -> CustomerName varchar(20), -> CustomerCountryName varchar(100) -> ); Query OK, 0 rows affected (1.05 sec)Following is the query to find in which tables a specific column “'CustomerCountryName'” is present −mysql> select *from information_schema.columns WHERE COLUMN_NAME = 'CustomerCountryName';OutputThis will produce the following output −+---------------+--------------+--------------+---------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+--------------+------------+-------+---------------------------------+----------------+-----------------------+-------+ | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME |ORDINAL_POSITION | COLUMN_DEFAULT | IS_NULLABLE | DATA_TYPE |CHARACTER_MAXIMUM_LENGTH | CHARACTER_OCTET_LENGTH |NUMERIC_PRECISION ...
Read MoreHow to order MySQL rows by multiple columns?
Let us first create a table −mysql> create table DemoTable -> ( -> FirstName varchar(20), -> LastName varchar(20) -> ); Query OK, 0 rows affected (1.44 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John', 'Smith'); Query OK, 1 row affected (0.35 sec) mysql> insert into DemoTable values('Chris', 'Brown'); Query OK, 1 row affected (0.37 sec) mysql> insert into DemoTable values('Carol', 'Taylor'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('David', 'Miller'); Query OK, 1 row affected (0.24 sec)Display all records from the table using ...
Read MoreSort a column ignoring a specific word in MySQL
Let us first create a table −mysql> create table DemoTable -> ( -> Name text -> ); Query OK, 0 rows affected (1.31 sec)Insert some records in the table using insert command. Here, we have inserted a name with a specific word “name”, which we need to ignore −mysql> insert into DemoTable values('John 7'); Query OK, 1 row affected (0.65 sec) mysql> insert into DemoTable values('John 6'); Query OK, 1 row affected (0.42 sec) mysql> insert into DemoTable values('John 9'); Query OK, 1 row affected (0.33 sec) mysql> insert into DemoTable values('name John 3'); ...
Read MoreHow to search a MySQL table for a specific string?
Use equal to operator for an exact match −select *from yourTableName where yourColumnName=yourValue;Let us first create a table −mysql> create table DemoTable -> ( -> FirstName varchar(100), -> LastName varchar(100) -> ); Query OK, 0 rows affected (0.70 secInsert some records in the table using insert command −mysql> insert into DemoTable values('John', 'Smith'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('John', 'Doe'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Chris', 'Brown'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Carol', 'Taylor'); Query OK, 1 row affected ...
Read MoreHow to update multiple rows and left pad values in MySQL?
Use the LPAD() function to left pad values. Let us first create a table −mysql> create table DemoTable -> ( -> Number int -> ); Query OK, 0 rows affected (2.26 secInsert some records in the table using insert command −mysql> insert into DemoTable values(857786); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values(89696); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(89049443); Query OK, 1 row affected (0.25 secDisplay all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+----------+ | ...
Read MoreChange the column name from StudentName to FirstName in MySQL?
Use CHANGE with ALTER statement. Let us first create a table −mysql> create table DemoTable -> ( -> StudentName varchar(100), -> Age int -> ); Query OK, 0 rows affected (0.84 sec)Now check the description of table −mysql> desc DemoTable;OutputThis will produce the following output −+----------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------+--------------+------+-----+---------+-------+ | StudentName | varchar(100) | YES | | NULL | | | Age ...
Read MoreFind and display duplicate values only once from a column in MySQL
Let us first create a table −mysql> create table DemoTable -> ( -> value int -> ); Query OK, 0 rows affected (0.82 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(100); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.34 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.24 sec) mysql> insert into ...
Read MoreIf I truncate a table, should I also add indexes?
If you truncate a table, you do not need to add indexes because table is recreated after truncating a table and indexes get added automatically.Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20), -> LastName varchar(20) -> ); Query OK, 0 rows affected (0.65 sec)Following is the query to create an index −mysql> create index Index_firstName_LastName on DemoTable(FirstName, LastName); Query OK, 0 rows affected (1.04 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command −mysql> ...
Read MoreMySQL query to return a substring after delimiter?
Use SUBSTRING() to return values after delimiter. Let us first create a table −mysql> create table DemoTable -> ( -> Title text -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John is good in MySQL, Sam is good in MongoDB, Mike is good in Java'); Query OK, 1 row affected (0.19 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-------------------------------------------------------------------+ | Title ...
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