Database Articles

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Add records from corresponding duplicate values in another column with MySQL

AmitDiwan
AmitDiwan
Updated on 28-Feb-2020 288 Views

For this, you can use the aggregate function SUM() along with the GROUP BY clause. Let us first create a table −mysql> create table DemoTable    -> (    -> Name varchar(20),    -> Value int    -> ); Query OK, 0 rows affected (2.08 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 50); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('David', 90); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Chris', 60); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('Bob', 100); Query ...

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UPDATE with logical AND operator in MySQL

AmitDiwan
AmitDiwan
Updated on 28-Feb-2020 492 Views

For this, you can use AND operator with WHERE clause. Let us first create a table −mysql> create table DemoTable1616     -> (     -> StudentId int,     -> StudentName varchar(20),     -> StudentMarks int     -> ); Query OK, 0 rows affected (0.44 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1616 values(101, 'Chris', 56); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1616 values(102, 'Bob', 87); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1616 values(103, 'David', 56); Query OK, 1 row affected (0.20 sec) ...

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How to get the count of both present and absent students for a year in MySQL?

AmitDiwan
AmitDiwan
Updated on 28-Feb-2020 1K+ Views

For this, you can use IF() along with aggregate function SUM(). Let us first create a table −mysql> create table DemoTable1617     -> (     -> Attendance varchar(20),     -> CurrentYear int     -> ); Query OK, 0 rows affected (0.48 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1617 values('Present', 2019); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1617 values('Absent', 2019); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1617 values('Absent', 2017); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1617 values('Present', 2019); Query ...

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Select total from a MySQL table based on month

AmitDiwan
AmitDiwan
Updated on 28-Feb-2020 319 Views

For this, you can use GROUP BY MONTH(). Let us first create a table −mysql> create table DemoTable1628     -> (     -> PurchaseDate date,     -> Amount int     -> ); Query OK, 0 rows affected (1.55 sec)Insert some records in the table using insert command.mysql> insert into DemoTable1628 values('2019-01-10', 1500); Query OK, 1 row affected (0.68 sec) mysql> insert into DemoTable1628 values('2019-10-10', 2000); Query OK, 1 row affected (0.61 sec) mysql> insert into DemoTable1628 values('2019-10-24', 100); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1628 values('2019-11-10', 500); Query OK, 1 row affected ...

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What happens to the current MySQL transaction if the session is killed by DBA?

Swarali Sree
Swarali Sree
Updated on 27-Feb-2020 796 Views

Suppose if a session is killed in the middle of a transaction then that current MySQL transaction will be rolled back by MySQL and ended. It means that all the database changes made in the current transaction will be removed. It is called n implicit rollback when the session is killed.ExampleSuppose we have the following values in the table ‘marks’mysql> Select * from marks; +------+---------+-----------+-------+ | Id   | Name    | Subject   | Marks | +------+---------+-----------+-------+ |    1 | Aarav   | Maths     |    50 | |    1 | Harshit | Maths   ...

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What are some frequently used mysqlimport options while uploading the data into MySQL table through command line?

usharani
usharani
Updated on 27-Feb-2020 198 Views

mysqlimport can be run with a number of options. Followings are some options for mysqlimport and their effect on import.OptionAction-r or –replaceCause imported rows to overwrite existing rows if they have the same unique key value.-i or –ignoreIgnore rows that have the same unique key value as existing rows.-f or –forceForce mysqlimport to continue inserting data even if errors are encountered.-l or --lock-tablesLock each table before importing (a good option on a busy server).-d or –deleteEmpty the table before inserting.--fields-terminated- by='char'Specify the separator used between values of the same row, default \t (tab).--fields-enclosed- by='char'Specify the delimiter that encloses each field; ...

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MySQL Order by a specific column x and display remaining values in ascending order

AmitDiwan
AmitDiwan
Updated on 26-Feb-2020 191 Views

Let us first create a table −mysql> create table DemoTable    -> (    -> MonthNumber int    -> ); Query OK, 0 rows affected (1.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(9); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values(6); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(8); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values(5); ...

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Delete a specific record from a MySQL table by using AND in WHERE clause

AmitDiwan
AmitDiwan
Updated on 26-Feb-2020 236 Views

MySQL AND is used in WHERE to fetch a record by filtering using multiple conditions. Let us first create a table−mysql> create table DemoTable    -> (    -> Id int,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(101, 'Chris'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(102, 'David'); Query OK, 1 row affected (0.51 sec) mysql> insert into DemoTable values(103, 'Bob'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement ...

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Sort records with special characters like '2321/78/54-6'

AmitDiwan
AmitDiwan
Updated on 26-Feb-2020 219 Views

To sort, use ORDER BY SUBSTRING(). Let us first create a table −mysql> create table DemoTable    -> (    -> Value varchar(40)    -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2321/78/54-6')    -> ; Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('2321/78/54-8'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('2321/78/54-5'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('2321/78/54-9'); Query OK, 1 row affected (0.21 sec)Display all records from the table using select statement ...

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Order VARCHAR records with string and numbers in MySQL

AmitDiwan
AmitDiwan
Updated on 26-Feb-2020 586 Views

For this, use ORDER BY clause. Let us first create a table −mysql> create table DemoTable    -> (    -> StudentCode varchar(20)    -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('101J'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('100A'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('100B'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values('101S'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('103M'); Query OK, 1 row affected (0.15 ...

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