MySQL Articles

Page 241 of 355

Delete multiple entries from a MySQL table

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 851 Views

To delete multiple entries from a MySQL table, use JOIN. Let us first create a table −mysql> create table DemoTabl(Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100)); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(FirstName) values('Chris'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(FirstName) values('Bob'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(FirstName) values('Mike'); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable(FirstName) values('Adam'); Query OK, 1 row affected (0.33 sec) mysql> insert into DemoTable(FirstName) values('Bob'); Query OK, 1 row ...

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How to merge rows in MySQL?

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 5K+ Views

To merge rows in MySQL, use GROUP_CONCAT().Let us first create a table−mysql> create table DemoTable734 (    Id int,    Name varchar(100) ); Query OK, 0 rows affected (0.73 sec)Insert some records in the table using insert command−mysql> insert into DemoTable734 values(101, 'John'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable734 values(102, 'John'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable734 values(103, 'Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable734 values(104, 'Chris'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable734 values(104, 'Chris'); Query OK, 1 row affected ...

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Search records on the basis of date in MySQL?

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 200 Views

Let us first create a table -mysql> create table DemoTable732 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, PassengerId int, PassengerName varchar(100), PassengerAge int, PassengerTravelDatetime datetime ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command -mysql> insert into DemoTable732(PassengerId, PassengerName, PassengerAge, PassengerTravelDatetime) values(110, 'Chris', 25, '2019-07-23 12:45:56'); Query OK, 1 row affected (0.40 sec) mysql> insert into DemoTable732(PassengerId, PassengerName, PassengerAge, PassengerTravelDatetime) values(120, 'Robert', 24, '2019-07-21 11:05:00'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable732(PassengerId, PassengerName, ...

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Convert string (varchar) to double in MySQL

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 2K+ Views

Let us first create a table:mysql> create table DemoTable731 (Value varchar(100)); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command -mysql> insert into DemoTable731 values('4.50'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable731 values('7.83'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable731 values('8.91'); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable731 values('560.34'); Query OK, 1 row affected (0.21 sec)Display all records from the table using select statement -mysql> select *from DemoTable731;This will produce the following output -+--------+ | Value | +--------+ | 4.50 ...

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Assign an SQL result to variable from prepared statement in MySQL?

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 2K+ Views

For this, use stored procedure. Let us first create a table −mysql> create table DemoTable(Id int, Name varchar(100)); Query OK, 0 rows affected (1.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10, 'John'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(11, 'Chris'); Query OK, 1 row affected (0.41 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+------+-------+ | Id | Name    | +------+-------+ | 10 | John    | | 11 | Chris | +------+-------+ 2 rows ...

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MySQL query to count days in date range with start and end date

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 919 Views

To count days in date range, you need to find the difference between dates using DATEDIFF().Let us first create a table:mysql> create table DemoTable730 (    StartDate date,    EndDate date ); Query OK, 0 rows affected (0.45 sec)Insert some records in the table using insert command:mysql> insert into DemoTable730 values('2019-01-21', '2019-07-21'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable730 values('2018-10-11', '2018-12-31'); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable730 values('2016-01-01', '2016-12-31'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement:mysql> select *from DemoTable730;This will produce the following ...

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Display the student marks in a single column on the basis of subject in MySQL?

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 2K+ Views

For this, use UNION ALL.Let us first create a table:mysql> create table DemoTable729 (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(100),    MySQLMarks int,    CMarks int,    JavaMarks int ); Query OK, 0 rows affected (0.40 sec)Insert some records in the table using insert command:mysql> insert into DemoTable729(StudentName, MySQLMarks, CMarks, JavaMarks) values('Chris', 94, 67, 75); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable729(StudentName, MySQLMarks, CMarks, JavaMarks) values('Robert', 45, 99, 54); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable729(StudentName, MySQLMarks, CMarks, JavaMarks) values('David', 57, 89, 43); Query OK, 1 row ...

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Selecting a value in custom order from another column in a MySQL table with a single query

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 175 Views

For this, you can use IN().Let us first create a table:mysql> create table DemoTable727 (    Name varchar(100),    Score int ); Query OK, 0 rows affected (0.88 sec)Insert some records in the table using insert command:mysql> insert into DemoTable727 values('Chris', 45); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable727 values('Robert', 89); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable727 values('Carol', 94); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable727 values('David', 93); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable727 values('Mike', 78); Query OK, 1 row affected (0.21 ...

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How to sort varchar numeric columns by DESC or ASC in MySQL?

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 590 Views

Let us first create a table −mysql> create table DemoTable726 (Value varchar(100)); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command −mysql> insert into DemoTable726 values('100'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable726 values('10'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable726 values('110'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable726 values('2000'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable726 values('1000'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select *from DemoTable726;This will ...

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Can we give underscore in a MySQL table name?

AmitDiwan
AmitDiwan
Updated on 22-Aug-2019 1K+ Views

You cannot give underscore in table name. If you still want to create a new table with underscore, surround it using backticks, not single quotes.However, let us first try to set quotes around a table name with underscore. Following is an example −mysql> create table 'Demo_Table725'(    ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ClientName varchar(100),    ClientAge int,    ClientCountryName varchar(100),    isMarried boolean );This will produce the following output i.e. an error since we haven’t used backtick −ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server ...

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