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Articles on Trending Technologies
Technical articles with clear explanations and examples
Best way to update a single column in a MySQL table?
To update a single column, use UPDATE and SET as in the below syntax −update yourTableName set yourColumnName=yourValue;Let us first create a table −mysql> create table DemoTable1873 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1873(FirstName) values('John'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1873(FirstName) values('Adam'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1873(FirstName) values('David'); Query OK, 1 row affected (0.00 sec) mysql> insert into ...
Read MoreMySQL query to SELECT rows with LIKE and create new column containing the matched string?
For this, use SUBSTRING(). Let us first create a table −mysql> create table DemoTable1872 ( Name varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1872 values('John Doe'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1872 values('Adam Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1872 values('Mitchell Johnson'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1872;This will produce the following output −+------------------+ | Name ...
Read MoreMySQL Datetime to add days?
Let us first create a table −mysql> create table DemoTable1871 ( ArrivalDate datetime ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1871 values('2019-12-19 7:45:00'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1871 values('2018-11-10 12:00:00'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1871 values('2019-01-31'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1871; This will produce the following output −+---------------------+ | ArrivalDate | ...
Read MoreGet first date from timestamp in MySQL group by another column with duplicate value
For this, you can use aggregate function MIN() and GROUP BY. Let us first create a table −mysql> create table DemoTable1870 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Value int, ShippingTimestamp varchar(100) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1870(Value, ShippingTimestamp) values(10, '1570645800'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1870(Value, ShippingTimestamp) values(10, '1546194600'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1870(Value, ShippingTimestamp) values(11, '1573324200'); Query OK, 1 row affected (0.00 ...
Read MoreConcatenate two values from the same column with different conditions in MySQL
For this, you can use group_concat() with aggregate function. Let us first create a table −mysql> create table DemoTable1869 ( Id int, Subject varchar(20 ), Name varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1869 values(100, 'MySQL', 'John'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1869 values(100, 'MongoDB', 'Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1869 values(101, 'MySQL', 'Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1869 values(101, ...
Read MoreHow to derive value of a field from another field in MySQL?
For this, you can use the concept of user defined variable. Let us first create a table −mysql> create table DemoTable1868 ( Value int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1868 values(10); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1868 values(20); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1868 values(30); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1868 values(40); Query OK, 1 row affected (0.00 sec)Display all records from the table using ...
Read MoreHow to list all variables initialized by SET operator in MySQL?
To list all variables initialized by SET operator, the syntax is as follows −select * from performance_schema.user_variables_by_thread;Here is the query to set the variable −mysql> set @FirstName='John'; Query OK, 0 rows affected (0.00 sec) mysql> set @LastName='Doe'; Query OK, 0 rows affected (0.00 sec)Here is the query to display the list of all variables initialized by SET operator. This list includes the variables set above −mysql> select * from performance_schema.user_variables_by_thread;This will produce the following output −+-----------+---------------+----------------+ | THREAD_ID | VARIABLE_NAME | VARIABLE_VALUE | +-----------+---------------+----------------+ | 120 | TotalAmount | 5000 | ...
Read MoreIncrement date/time value by second with MySQL query?
For this, use date_add() with interval command. Let us first create a table −mysql> create table DemoTable1867 ( ArrivalTime datetime ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1867 values('2019-10-12 12:34:45'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1867 values('2019-10-12 10:04:15'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1867 values('2019-10-12 11:00:23'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1867; This will produce the following output ...
Read MoreMySQL query to get string from one column and find its position in another column with comma separated values?
For this, use FIND_IN_SET(). Let us first create a table −mysql> create table DemoTable1866 ( Value1 int, ListOfValues varchar(100) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1866 values(56, '78, 56, 98, 95'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1866 values(103, '103, 90, 102, 104'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1866 values(77, '34, 45, 77, 78'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> ...
Read MoreHow to assign the result of a MySQL query into a variable?
Use @anyVariableName to assign the result of a query into a variable. Let us first create a table −mysql> create table DemoTable1864 ( Id int, FirstName varchar(20), LastName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1864 values(101, 'Chris', 'Brown'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1864 values(102, 'David', 'Miller'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1864 values(103, 'Adam', 'Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into ...
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