MySQL Articles

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How to select distinct value from one MySQL column only?

Nishtha Thakur
Nishtha Thakur
Updated on 30-Jul-2019 2K+ Views

To select distinct value from one column only, you can use aggregate function MAX() along with GROUP BY. Let us first create a table −mysql> create table distinctFromOneColumn    -> (    -> StudentId int,    -> StudentName varchar(100)    -> ); Query OK, 0 rows affected (0.77 sec)Following is the query to insert records in the table using insert command −mysql> insert into distinctFromOneColumn values(1001, 'John'); Query OK, 1 row affected (0.15 sec) mysql> insert into distinctFromOneColumn values(1002, 'Carol'); Query OK, 1 row affected (0.15 sec) mysql> insert into distinctFromOneColumn values(1001, 'Sam'); Query OK, 1 row affected ...

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How to calculate value from multiple columns in MySQL?

Anvi Jain
Anvi Jain
Updated on 30-Jul-2019 1K+ Views

To calculate a value from multiple columns, use GROUP BY. Following is the syntax −select yourColumnName1, sum(yourColumnName2*yourColumnName3) AS anyAliasName from yourTableName group by yourColumnName1;Let us first create a table −mysql> create table calculateValueDemo    -> (    -> Id int,    -> ProductPrice int,    -> ProductWeight int    -> ); Query OK, 0 rows affected (0.56 sec)Following is the query to insert records in the table using insert command −mysql> insert into calculateValueDemo values(100, 35, 5); Query OK, 1 row affected (0.16 sec) mysql> insert into calculateValueDemo values(101, 50, 3); Query OK, 1 row affected (0.16 sec) ...

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MySQL select only duplicate records from database and display the count as well?

Smita Kapse
Smita Kapse
Updated on 30-Jul-2019 451 Views

To select only duplicate records from database and display the count, use HAVING along with aggregate function count(). Let us first create a table −mysql> create table duplicateRecords    -> (    -> ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> ClientName varchar(20)    -> ); Query OK, 0 rows affected (0.49 sec)Following is the query to insert records in the table using insert command −mysql> insert into duplicateRecords(ClientName) values('John'); Query OK, 1 row affected (0.16 sec) mysql> insert into duplicateRecords(ClientName) values('Carol'); Query OK, 1 row affected (0.17 sec) mysql> insert into duplicateRecords(ClientName) values('John'); Query OK, 1 row affected ...

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How to compare timestamps in MySQL?

Nishtha Thakur
Nishtha Thakur
Updated on 30-Jul-2019 4K+ Views

To compare timestamps in MySQL, you can use DATE(). Let us first create a table−mysql> create table comparingTimestampDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> AdmissionDate timestamp    -> ); Query OK, 0 rows affected (0.54 sec)Following is the query to insert records in the table using insert command −mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-03-31'); Query OK, 1 row affected (0.13 sec) mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-04-10'); Query OK, 1 row affected (0.12 sec) mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-04-15'); Query OK, 1 row affected (0.17 sec) mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-03-29'); Query OK, 1 ...

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Can we GROUP BY one column and select all data in MySQL?

Smita Kapse
Smita Kapse
Updated on 30-Jul-2019 1K+ Views

Yes, you can use group_concat() for this. Let us first create a table −mysql> create table groupByOneSelectAll    -> (    -> StudentDetails varchar(100),    -> StudentName varchar(100)    -> ); Query OK, 0 rows affected (0.91 sec)Following is the query to insert some records in the table using insert command −mysql> insert into groupByOneSelectAll values('StudentFirstName', 'John'); Query OK, 1 row affected (0.14 sec) mysql> insert into groupByOneSelectAll values('StudentFirstName', 'Chris'); Query OK, 1 row affected (0.21 sec) mysql> insert into groupByOneSelectAll values('StudentFirstName', 'Robert'); Query OK, 1 row affected (0.65 sec) mysql> insert into groupByOneSelectAll values('StudentFirstName', 'Bob'); Query ...

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Add10 minutes to MySQL datetime format?

Nishtha Thakur
Nishtha Thakur
Updated on 30-Jul-2019 443 Views

Use DATE_ADD() to add 10 minutes to datetime format. Following is the syntax −select date_add(yourColumnName ,interval 10 minute) from yourTableName;Let us first create a table −mysql> create table add10MinuteDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> DelayDatetime datetime    -> ); Query OK, 0 rows affected (0.83 sec)Following is the query to insert records in the table using insert command −mysql> insert into add10MinuteDemo(DelayDatetime) values('2019-01-23 12:45:56'); Query OK, 1 row affected (0.16 sec) mysql> insert into add10MinuteDemo(DelayDatetime) values('2019-03-25 10:30:23'); Query OK, 1 row affected (0.19 sec) mysql> insert into add10MinuteDemo(DelayDatetime) values('2019-04-21 04:04:30'); Query ...

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MySQL format time with lowercase am/pm?

Anvi Jain
Anvi Jain
Updated on 30-Jul-2019 817 Views

To format MySQL time with lowercase am/pm, use the LOWER() as well as DATE_FORMAT().Let us first create a table −mysql> create table formatTime    -> (    -> LoginTime time    -> ); Query OK, 0 rows affected (0.56 sec)Following is the query to insert records in the table using insert command −mysql> insert into formatTime values('12:40:34'); Query OK, 1 row affected (0.20 sec) mysql> insert into formatTime values('14:10:58'); Query OK, 1 row affected (0.13 sec) mysql> insert into formatTime values('16:56:40'); Query OK, 1 row affected (0.18 sec) mysql> insert into formatTime values('10:12:14'); Query OK, 1 row ...

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Reorder integer except for value 0 with MySQL?

Anvi Jain
Anvi Jain
Updated on 30-Jul-2019 146 Views

To reorder integer except for value 0, use the below syntax −select *from yourTableName order by yourColumnName=0 ,yourColumnName;Let us first create a table −mysql> create table reorderIntegerExcept0    -> (    -> value int    -> ); Query OK, 0 rows affected (0.70 sec)Following is the query to insert records in the table using insert command −mysql> insert into reorderIntegerExcept0 values(90); Query OK, 1 row affected (0.17 sec) mysql> insert into reorderIntegerExcept0 values(10); Query OK, 1 row affected (0.21 sec) mysql> insert into reorderIntegerExcept0 values(0); Query OK, 1 row affected (0.18 sec) mysql> insert into reorderIntegerExcept0 values(40); ...

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Select results from the middle of a sorted list in MySQL?

Smita Kapse
Smita Kapse
Updated on 30-Jul-2019 1K+ Views

To select results from the middle of a sorted list, use ORDER BY clause along with LIMIT.Let us first create a table. Following is the query −mysql> create table sortedListDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> StudentName varchar(100)    -> ); Query OK, 0 rows affected (0.46 sec)Following is the query to insert some records in the table using insert command −mysql> insert into sortedListDemo(StudentName) values('John'); Query OK, 1 row affected (0.62 sec) mysql> insert into sortedListDemo(StudentName) values('Sam'); Query OK, 1 row affected (0.18 sec) mysql> insert into sortedListDemo(StudentName) values('Adam'); ...

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Difference between count(*) and count(columnName) in MySQL?

George John
George John
Updated on 30-Jul-2019 3K+ Views

The count(*) returns all rows whether column contains null value or not while count(columnName) returns the number of rows except null rows.Let us first create a table.Following is the querymysql> create table ifNotNullDemo    -> (    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.54 sec)Following is the query to insert some records in the table using insert command:mysql> insert into ifNotNullDemo values('Chris'); Query OK, 1 row affected (0.15 sec) mysql> insert into ifNotNullDemo values(''); Query OK, 1 row affected (0.13 sec) mysql> insert into ifNotNullDemo values('Robert'); Query OK, 1 row affected (0.24 sec) ...

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