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Database Articles
Page 340 of 547
Adding unique constraint to ALTER TABLE in MySQL
Let us first create a table −mysql> create table DemoTable1811 ( FirstName varchar(20), LastName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Here is the query to add indexmysql> alter table DemoTable1811 ADD UNIQUE unique_index_first_last_name(FirstName, LastName); Query OK, 0 rows affected (0.00 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command −mysql> insert into DemoTable1811 values('John', 'Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1811 values('John', 'Doe'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1811 values('Adam', 'Smith'); Query OK, 1 ...
Read MoreFetch a specific column value (name) in MySQL
To fetch a specific column value, use LIKE clause. Let us first create a table −mysql> create table DemoTable1809 ( Name varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1809 values('John'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1809 values('David'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1809 values('Mike'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1809 values('Johnson'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement ...
Read MoreDisplay all the column values in a single row separated by comma in MySQL?
For this, use GROUP_CONCAT() and CONCAT(). Let us first create a table −mysql> create table DemoTable1807 ( Id int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1807 values(101); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1807 values(102); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1807 values(103); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1807;This will produce the following output −+------+ | Id | ...
Read MoreHow to select rows in MySQL that are >= 1 DAY from the current date?
To get data greater than equal to 1 day from the current date, use the concept of INTERVAL in MySQL.The current date is as follows −mysql> select curdate(); +------------+ | curdate() | +------------+ | 2019-11-29 | +------------+ 1 row in set (0.00 sec)We will first create a table −mysql> create table DemoTable1806 ( DueDate datetime ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1806 values('2019-11-28'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1806 values('2019-11-29'); Query OK, 1 row affected (0.00 ...
Read MoreHow to use CONTAINS() with CURDATE in MySQL?
For this, you can use CONCAT() with CURDATE().There is no function with the name CONTAINS() in MySQL.Let us first get the current date. The current date is as follows −mysql> select curdate();This will produce the following output −+------------+ | curdate() | +------------+ | 2019-11-28 | +------------+ 1 row in set (0.00 sec)We will now create a table −mysql> create table DemoTable1803 ( Name varchar(20), JoiningYear varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1803 values('Chris', '2020/2017'); Query OK, 1 row ...
Read MoreMySQL group by for separate id without using GROUP BY to remove duplicate column row?
For this, you can use DISTINCT keyword. Let us first create a table −mysql> create table DemoTable1801 ( Name varchar(20), Score int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1801 values('John', 98); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1801 values('John', 98); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1801 values('John', 99); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1801 values('Carol', 99); Query OK, 1 row affected (0.00 sec)Display all records ...
Read MoreFind sum with MySQL SUM() and give aliases for column heading
For alias, use the following syntax wherein we are display an alias name −select sum(yourColumnName) as anyAliasName from yourTableName;Let us first create a table −mysql> create table DemoTable1800 ( Salary int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1800 values(18000); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1800 values(32000); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1800 values(50000); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * ...
Read MoreHow to quote values of single column using GROUP_CONCAT and CONCAT with DISTINCT in MySQL?
For this, you can use group_concat() along with replace(). Let us first create a table −mysql> create table DemoTable1799 ( EmployeeId varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1799 values('101, 102, 103, 104'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1799 values('106, 109'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1799;This will produce the following output:+-----------------+ | EmployeeId | +-----------------+ | 101, 102, 103, ...
Read MoreHow to display two different sums of the same price from column Amount in MySQL?
For this, you can use case statement. Let us first create a table −mysql> create table DemoTable1794 ( Amount int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1794 values(100); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1794 values(80); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1794 values(320); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1794;This will produce the following output −+--------+ | Amount | ...
Read MoreHow do I select data that does not have a null record in MySQL?
To select not-null records, use IS NOT NULL property. Let us first create a table −mysql> create table DemoTable1792 ( Name varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1792 values('John Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1792 values(NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1792 values('David Miller'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1792 values(NULL); Query OK, 1 row affected (0.00 sec)Display all records from the table using ...
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