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Technical articles with clear explanations and examples

Using MySQL where clause and ordering by avg() to find the average of duplicate individual elements

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 307 Views

For this, use having clause instead of where. Let us first create a table −mysql> create table DemoTable1338    -> (    -> Name varchar(10),    -> Score int    -> ); Query OK, 0 rows affected (1.54 sec)Insert some records in the table using insert command. Here, we have inserted duplicate names with scores −mysql> insert into DemoTable1338 values('Chris', 8); Query OK, 1 row affected (0.80 sec) mysql> insert into DemoTable1338 values('Bob', 4); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1338 values('Bob', 9); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable1338 values('Chris', 6); ...

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Fetch maximum value from a column with values as string numbers like Value440, Value345, etc. in SQL

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 188 Views

For this, you can use MAX() along with substring(). Let us first create a table −mysql> create table DemoTable1337    -> (    -> Value varchar(50)    -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1337 values('Value400'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1337 values('Value345'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1337 values('Value567'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1337 values('Value489'); Query OK, 1 row affected (0.22 sec)Display all records from the table using select statement ...

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Select different fields in MySQL even if a field is set to null?

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 262 Views

For this, you can use COALESCE(). Let us first create a table −mysql> create table DemoTable1336    -> (    -> FirstName varchar(20)    -> ,    -> SecondName varchar(20)    -> ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1336 values('John', NULL); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1336 values(NULL, 'Chris'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1336 values('David', 'Mike'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select * from DemoTable1336;This ...

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Select entries with timestamp after X time in MySQL

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 533 Views

Let us first create a table −mysql> create table DemoTable1335    -> (    -> ArrivalTime datetime    -> ); Query OK, 0 rows affected (0.49 sec)Insert some records in the table using insert command. We have inserted date time records here −mysql> insert into DemoTable1335 values('2019-09-19 22:54:00'); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable1335 values('2019-09-19 22:59:00'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1335 values('2019-09-19 22:56:00'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1335 values('2019-09-19 22:52:00'); Query OK, 1 row affected (0.11 sec)Display all records from the table using ...

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Insert values in two tables with a single stored procedure call in MySQL

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 2K+ Views

Following is the syntax to insert values in two tables with a stored procedure −DELIMITER // CREATE PROCEDURE yourProcedureName(anyVariableName int)    BEGIN    insert into yourTableName1(yourColumnName1) values(yourVariableName);    insert into yourTableName2(yourColumnName2) values(yourVariableName);    END //Let us first create a table −mysql> create table DemoTable1    -> (    -> StudentScore int    -> ); Query OK, 0 rows affected (0.58 sec)Following is the second table −mysql> create table DemoTable2    -> (    -> PlayerScore int    -> ); Query OK, 0 rows affected (0.52 sec)Here is the query to create a stored procedure and insert values in two tables ...

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MySQL row declarations for ZF?

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 361 Views

The ZF stands for ZEROFILL i.e. row declarations for zero fill Let us first create a table. Here, we have set the int field size to be 10 −mysql> create table DemoTable1332    -> (    -> Number int(10) ZEROFILL NOT NULL DEFAULT 0    -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1332 values(); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1332 values(1); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1332 values(10); Query OK, 1 row affected (0.10 sec) mysql> insert ...

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How do I use the @ sign in MySQL?

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 568 Views

To use the @ sign, use MySQL SET command. The @sign is used to set user-defined variables. Following is the syntax −SET @anyVariableName:=yourValue;Let us first create a table −mysql> create table DemoTable1331    -> (    -> Id int,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1331 values(10, 'Chris'); Query OK, 1 row affected (0.71 sec) mysql> insert into DemoTable1331 values(101, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1331 values(40, 'Bob'); Query OK, 1 row affected (0.12 sec) ...

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How to TRIM x number of characters, beginning from the last in MySQL?

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 392 Views

For this, you can use substring() along with length(). Let us first create a table −mysql> create table DemoTable1329    -> (    -> StudentName varchar(40)    -> ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1329 values('David Miller'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1329 values('Chris Brown'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1329 values('Adam Smith'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable1329 values('John Doe'); Query OK, 1 row affected (0.44 sec)Display all records from the ...

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MySQL query to extract time in a format without seconds

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 477 Views

For this, you can use time_format(). Let us first create a table −mysql> create table DemoTable1326    -> (    -> Arrivaltime time    -> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1326 values('12:10:45'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1326 values('20:00:00'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1326 values('22:45:55'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1326 values('04:10:24'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select * ...

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Order MySQL results without identifier?

AmitDiwan
AmitDiwan
Updated on 05-Nov-2019 219 Views

To order MySQL results without identifier, the syntax is as follows −select * from yourTableName order by 1 DESC LIMIT yourLimitValue;Let us first create a table −mysql> create table DemoTable1325    -> (    -> Id int,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1325 values(100, 'Chris'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1325 values(101, 'Bob'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1325 values(120, 'David'); Query OK, 1 row affected (0.14 sec) mysql> insert ...

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