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MySQL Articles
Page 261 of 355
Update all rows by prefixing a line to every text in MySQL?
For this, use the CONCAT() function. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Subject varchar(200) ); Query OK, 0 rows affected (1.36 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Subject) values('MySQL'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Subject) values('MongoDB'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(Subject) values('Java'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+----+---------+ | Id | Subject | +----+---------+ ...
Read MoreHow to delete '' entry in MySQL?
You can use delete command −delete from yourTableName where yourColumnName='\';Let us first create a table −mysql> create table DemoTable ( FolderName varchar(100) ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values("????"); Query OK, 1 row affected (0.44 sec) mysql> insert into DemoTable values("\"); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+------------+ | FolderName | +------------+ | ???? | | \ ...
Read MoreMySQL query to insert current date plus specific time?
You can use CONCAT() for this. The syntax is as follows −insert into DemoTable values(concat(curdate(), ' yourSpecificTime’));Let us first create a table −mysql> create table DemoTable ( ArrivalDate datetime ); Query OK, 0 rows affected (1.06 sec)Insert some records in the table using insert command. We are adding the current date and time −mysql> insert into DemoTable values(concat(curdate(), ' 10:20:05')); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(concat(curdate(), ' 12:05:00')); Query OK, 1 row affected (0.17 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+---------------------+ | ArrivalDate ...
Read MoreMySQL query to select date >= current date - 3 weeks?
Use the concept of DATE_SUB(). Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, ArrivalDate datetime ); Query OK, 0 rows affected (1.02 sec)Note: Let’s say the current date is 2019-06-08Insert some records in the table using insert command −mysql> insert into DemoTable(ArrivalDate) values('2019-05-15'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(ArrivalDate) values('2019-06-08'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable(ArrivalDate) values('2019-05-20'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(ArrivalDate) values('2019-05-12'); Query OK, 1 row affected (0.12 sec)Display ...
Read MoreSelect specific rows in a range with MySQL?
Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(20) ); Query OK, 0 rows affected (1.23 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentName) values('John'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(StudentName) values('Carol'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(StudentName) values('David'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(StudentName) values('Bob'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(StudentName) values('Chris'); Query OK, 1 row affected (0.12 sec) ...
Read MoreSet all values in a MySQL field to 0?
To set all the values in a field to 0, use the update command −update yourTableName set yourColumnName=0;Let us first create a table −mysql> create table DemoTable ( Number int ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(4757); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(48474); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values(35465); Query OK, 1 row affected (0.16 sec)Display all records from ...
Read MoreHow can I update a field in a MySQL database table by adding a value in the second table with a value from the first table?
Let us first create a table −mysql> create table DemoTable1 ( value int ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(10); Query OK, 1 row affected (0.17 sec)Display all records from the table using select statement −mysql> select *from DemoTable1;Output+-------+ | value | +-------+ | 10 | +-------+ 1 row in set (0.00 sec)Following is the query to create second table −mysql> create table DemoTable2 ( value1 int ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table ...
Read MoreAdding a new column with the current time as a default value in MySQL?
For this, you can use the DEFAULT CURRENT_TIMESTAMP clause in MySQL. Following is the syntax −CREATE TABLE yourTableName ( yourColumnName1 dataType1, yourColumnName timestamp DEFAULT CURRENT_TIMESTAMP );Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> DueDate timestamp default current_timestamp -> ); Query OK, 0 rows affected (0.86 sec)Now you can insert some records in the table using insert command −mysql> insert into DemoTable values(); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+----+---------------------+ ...
Read MoreSelect column names containing a string in MySQL?
For this, you can use SHOW COLUMNS command. Following is the syntax. Here, we have set the string using LIKE −SHOW COLUMNS FROM yourTableName LIKE ‘yourStringValue’;Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20), -> LastName varchar(20) -> ); Query OK, 0 rows affected (0.69 sec)Here is the query to select column names containing a specific string −mysql> SHOW COLUMNS FROM DemoTable LIKE 'FirstName';Output+-----------+-------------+------+-----+----------+-------+ | Field | Type | Null | ...
Read MoreFind the greatest value among four tables in MySQL?
To find the greatest value among four tables, you can use the method GREATEST(). Following is the query to create first table −mysql> create table DemoTable1 -> ( -> Value int -> ); Query OK, 0 rows affected (0.70 sec)Insert some records in the first table using insert command −mysql> insert into DemoTable1 values(10); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1 values(60); Query OK, 1 row affected (0.14 sec)Display all records from the first table using select statement −mysql> select *from DemoTable1;Output+-------+ | Value | +-------+ | 10 | ...
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