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Database Articles
Page 362 of 547
MySQL query to calculate the days between two dates from different columns but similar rows
Let us first create a table −mysql> create table DemoTable1471 -> ( -> EmployeeJoiningDate date, -> EmployeeRelievingDate date -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1471 values('2018-06-21', '2018-12-21'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1471 values('2017-01-19', '2019-01-31'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1471 values('2015-12-31', '2016-03-01'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select * from DemoTable1471;This will produce the following output −+---------------------+-----------------------+ | EmployeeJoiningDate | ...
Read MoreSelect a field and if it's null, select another with MySQL?
For this, use COALESCE(). Let us first create a table −mysql> create table DemoTable1470 -> ( -> FirstName varchar(20), -> Age int -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1470 values('Robert', 23); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable1470 values('Bob', NULL); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1470 values(NULL, 25); Query OK, 1 row affected (0.15 sec)Display all records from the table using select statement −mysql> select * from DemoTable1470;This will produce the following output ...
Read MoreRemove index from a MySQL table
To remove index from a MySQL table, the syntax is as follows −alter table yourTableName drop index `yourIndexName`;Let us first create a table −Mysql> create table DemoTable1469 -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(40), -> StudentAge int -> ); Query OK, 0 rows affected (0.78 sec)Following is the query to add index on column name −mysql> create index `Student Name_Index` on DemoTable1469(StudentName); Query OK, 0 rows affected (0.33 sec) Records: 0 Duplicates: 0 Warnings: 0Let us check the table description −mysql> desc DemoTable1469;This will produce the following output −+-------------+-------------+------+-----+---------+----------------+ ...
Read MoreDelete rows with duplicate and similar content & get row with maximum number with MySQL select statement?
Let us first create a table −mysql> create table DemoTable1468 -> ( -> Id int, -> Name varchar(20), -> Age int -> ); Query OK, 0 rows affected (1.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1468 values(100, 'Chris', 23); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1468 values(101, 'Bob', 25); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1468 values(102, 'David', 30); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1468 values(100, 'Chris', 23); Query OK, 1 row affected (0.35 sec) mysql> ...
Read MoreGet rows that have common value from the same table with different id in MySQL
For this, you can use GROUP BY HAVING clause. Let us first create a table −mysql> create table DemoTable1467 -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1467 values(100, 'Chris'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1467 values(110, 'David'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1467 values(120, 'Mike'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1467 values(100, 'Chris'); Query OK, 1 row affected (0.12 sec) ...
Read MoreFastest way to insert with multiple values in a single MySQL query?
Do not use the below query for this −insert into yourTableName values(yourValue1, yourValue2, ...N); insert into yourTableName values(yourValue1, yourValue2, ...N); insert into yourTableName values(yourValue1, yourValue2, ...N); . . . NYou can use below query as the fastest way to insert with multiple values in a single query −insert into yourTableName values(yourValue1, yourValue2, ...N), (yourValue1, yourValue2, ...N), (yourValue1, yourValue2, ...N), ...................N;Let us first create a table −mysql> create table DemoTable1466 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(20), -> Age int -> ); Query OK, 0 rows affected (0.98 sec)Insert some records ...
Read MoreHow to split string in MySQL using SUBSTRING_INDEX?
Let us first create a table −mysql> create table DemoTable1465 -> ( -> Name varchar(40) -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1465 values('Chris Brown'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1465 values('David Miller'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable1465 values('John Doe'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select * from DemoTable1465;This will produce the following output −+--------------+ | Name | ...
Read MoreImplement DELETE query in MySQL stored procedure
You can use stored procedure and can pass the value via parameter. Let us first create a table −mysql> create table DemoTable1464 -> ( -> Id int, -> FirstName varchar(20) -> ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1464 values(101, 'Chris Brown'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1464 values(102, 'John Doe'); Query OK, 1 row affected (0.09 sec)Display all records from the table using select statement −mysql> select * from DemoTable1464;This will produce the following output −+------+-------------+ | Id ...
Read MoreConcatenate multiple rows and columns in a single row with MySQL
To concatenate multiple rows and columns in single row, you can use GROUP_CONCAT() along with CONCAT(). Let us first create a table −mysql> create table DemoTable1463 -> ( -> ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ClientName varchar(20), -> ClientAge int -> ); Query OK, 0 rows affected (1.37 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1463(ClientName, ClientAge) values('Adam Smith', 34); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1463(ClientName, ClientAge) values('John Doe', 29); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1463(ClientName, ClientAge) values('David ...
Read MorePerform mathematical calculations in a MySQL table with NULL and NON-NULL values
For this, you can use IFNULL() and perform mathematical calculations with NULL and NON-NULL values. Let us first create a table −mysql> create table DemoTable1462 -> ( -> Value1 int, -> Value2 int -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1462 values(10, 20); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1462 values(50, NULL); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1462 values(NULL, 70); Query OK, 1 row affected (0.25 sec)Display all records from the table using select ...
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