Database Articles

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How to correctly use DELIMITER in a MySQL stored procedure?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 407 Views

The correct way is as follows −DELIMITER // CREATE PROCEDURE yourStoredProcedureName() BEGIN  IF  yourCondition then      yourStatement1 ; else     yourStatement2 ; END IF ; END // DELIMITER ;Let us now see an example and create a stored procedure −mysql> DELIMITER // mysql> CREATE PROCEDURE delimiter_demo()    -> BEGIN    -> IF 1 THEN    -> SELECT "If condition will always true";    -> else    -> select "No" ;    -> END IF ;    -> END    -> // Query OK, 0 rows affected (0.17 sec) mysql> DELIMITER ;Now you can call the ...

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Select the minimum value from the maximum values of two tables with a single MySQLnquery?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 228 Views

For this, you can use UNION in MySQL. Let us first create a table −mysql> create table DemoTable1    -> (    -> Value int    -> )    -> ; Query OK, 0 rows affected (0.48 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(60); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1 values(78); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1 values(57); Query OK, 1 row affected (0.08 sec)Display all records from the table using select statement −mysql> select * from DemoTable1; This will produce the following ...

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What are the minimum MySQL user privileges to allow optimize and repair?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 446 Views

The select and insert statements are the minimum required MySQL user privileges to allow optimize and repair.You can use below syntax to give insert and select privileges to the user −grant insert, select on yourDatabaseName.* to 'yourUserName'@'localhost';At first, here is the query to create a user −mysql> create user 'Emma'@'localhost' identified by 'Emma123'; Query OK, 0 rows affected (0.26 sec)Here is the query to give grants for the above user −mysql> grant insert, select on web.* to 'Emma'@'localhost'; Query OK, 0 rows affected (0.21 sec)Here is the query to display all grants of the above user −mysql> show grants for ...

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Query for implementing MySQL LIKE as MySQL IN?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 237 Views

To implement a query like MySQL IN(), you need to use COUNT(), IF() along with LIKE operator. Let us first create a table −mysql> create table DemoTable    -> (    -> Subject varchar(80)    -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('MySQLMongoDB'); Query OK, 1 row affected (0.86 sec) mysql> insert into DemoTable values('MySQL'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('JavaMySQL'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('MongoDB'); Query OK, 1 row affected (0.20 sec) ...

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Fetch maximum value from multiple columns with null and non-null values?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 504 Views

For this, you can use COALESCE(). For the maximum value, use GREATEST() in MySQL. Let us first create a table −mysql> create table DemoTable    -> (    -> Value1 int,    -> Value2 int,    -> Value3 int    -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(NULL, 80, 76); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(NULL, NULL, 100); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(56, NULL, 45); Query OK, 1 row affected (0.20 sec) mysql> ...

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Format MySQL records (price values) after multiplying them

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 230 Views

To format records, use FORMAT(). Let us first create a table −mysql> create table DemoTable    -> (    -> Price decimal(10, 4),    -> Rate decimal(10, 4)    -> ); Query OK, 0 rows affected (0.96 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(1000, 10.2); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(2000, 20.4); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(100, 5); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the ...

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MySQL LIKE command doesn't work with strings containing dots to display records beginning with a specific number

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 552 Views

To work with strings containing dots, and display records beginning with a specific number, you need to use REGEXP. Let us first create a table −mysql> create table DemoTable    -> (    -> GameReleaseVersion varchar(20)    -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('19.6'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('18.4'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('17.6'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('19.5'); Query OK, 1 row affected ...

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MySQL query to fetch records before currentdate + 2 weeks?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 832 Views

For this, use the below syntax −select * from yourTableName where yourColumnName < DATE_ADD(CURDATE(), INTERVAL 2 WEEK);Note: The current date is as follows −mysql> select curdate(); +------------+ | curdate()  | +------------+ | 2019-10-20 | +------------+ 1 row in set (0.00 sec)Let us first create a table −mysql> create table DemoTable1607    -> (    -> ShippingDate date    -> )    -> ; Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1607 values('2019-10-20'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1607 values('2019-11-04'); Query OK, 1 row affected ...

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Implement Harmonic mean and Quadratic mean in MySQL?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 182 Views

Let us first create a table −mysql> create table DemoTable1606    -> (    -> Value int    -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1606 values(5); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1606 values(10); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select * from DemoTable1606;This will produce the following output −+-------+ | Value | +-------+ |     5 | |    10 | +-------+ 2 rows in set (0.00 sec)Here is the ...

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MySQL update column to NULL for blank values

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 3K+ Views

For this, you can use IF() along with UPDATE command. Let us first create a table −mysql> create table DemoTable1601    -> (    -> FirstName varchar(20) ,    -> LastName varchar(20)    -> ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1601 values('John', 'Doe'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1601 values('Adam', ''); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1601 values('David', 'Miller'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1601 values('Chris', ''); Query OK, 1 row affected ...

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