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Technical articles with clear explanations and examples

How to replace a character in a MySQL table?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 422 Views

To replace only a single character, use REPLACE() in MySQL. Let us first create a table −mysql> create table DemoTable    -> (    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John Smitk'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values('David Miller'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Adam Smitk'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following ...

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How to implement MySQL ORDER BY x where (x=col3 if col3!=null, else x=col2)?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 155 Views

For this, you can use ORDER BY IFNULL(). Let us first create a table −mysql> create table DemoTable    -> (    -> Name varchar(20),    -> CountryName varchar(20)    -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', NULL); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('David', 'AUS'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(NULL, 'UK'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(NULL, 'AUS'); Query OK, 1 row affected (0.10 sec) mysql> ...

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What would happen if we insert empty values in a table with a column set as type TIMESTAMP CURRENT_TIMESTAMP?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 361 Views

If we will insert nothing in the INSERT statement, then for timestamp type, it would insert the current date-time. Let us first create a table −mysql> create table DemoTable    -> (    -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> UserLoginDate timestamp default current_timestamp    -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(); Query OK, 1 row affected (0.08 ...

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Sort items in MySQL with dots?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 198 Views

Let us first create a table −mysql> create table DemoTable    -> (    -> Value varchar(20)    -> ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('20'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('10.5'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('11'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('10'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('20.5'); Query OK, 1 row affected (0.13 sec)Display all records from the table ...

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The easiest way to insert date records in MySQL?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 284 Views

Use the STR_TO_DATE() method to insert date records as in the below syntax −select str_to_date(yourColumnName, '%b %Y') from yourTableName;Let us first create a table −mysql> create table DemoTable    -> (    -> JoiningYear varchar(20)    -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Jan 2018'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('May 2107'); Query OK, 1 row affected (0.32 sec) mysql> insert into DemoTable values('Aug 2019'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Oct 2020'); Query OK, ...

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Implement MySQL REGEXP to fetch records with . and numbers

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 175 Views

Let us first create a table −mysql> create table DemoTable    -> (    -> Version varchar(20)    -> ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('1.0.0'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('2.s6.9'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('1.5.0'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+---------+ | Version | +---------+ | 1.0.0   | | 2.s6.9  | ...

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MySQL query to display only 15 words from the left?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 125 Views

For this, use LEFT in MySQL. Let us first create a table −mysql> create table DemoTable    -> (    -> Title text    -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Java database connectivity to MySQL database'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Python with django framework'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('C with data structure and algorithm'); Query OK, 1 row affected (0.33 sec)Display all records from the table using select statement −mysql> select ...

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Replacing numbers on a comma delimited result with MySQL?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 312 Views

For this, use CASE statement along with FIND_IN_SET(). Let us first create a table −mysql> create table DemoTable1629     -> (     -> Month varchar(100)     -> ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command.mysql> insert into DemoTable1629 values('2, 4, 6'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1629 values('1, 3, 5, 12'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1629 values('7, 8, 9, 10'); Query OK, 1 row affected (0.15 sec)Display all records from the table using select statement − mysql> select ...

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Create MySQL datetime column with default 0000-00-00?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 867 Views

To set default, you can use the DEFAULT keyword in MySQL. Let us first create a table −mysql> create table DemoTable    -> (    -> EmployeeId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> EmployeeName varchar(20),    -> EmployeeJoiningDate datetime default '0000-00-00 00:00:00'    -> )ENGINE=MyISAM, AUTO_INCREMENT=100; Query OK, 0 rows affected (0.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(EmployeeName) values('Chris'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(EmployeeName) values('David'); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(EmployeeName) values('Mike'); Query OK, 1 row affected (0.03 sec) mysql> ...

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MySQL query to get a single value from position of comma-separated string?

AmitDiwan
AmitDiwan
Updated on 17-Dec-2019 563 Views

For this, use SUBSTRING_INDEX(). Let us first create a table −mysql> create table DemoTable1615    -> (    -> ListOfSubject text    -> ); Query OK, 0 rows affected (0.81 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1615 values('Python, Java, MySQL, MongoDB, C, C++, ASP.net'); Query OK, 1 row affected (0.19 sec)Display all records from the table using select statement −mysql> select * from DemoTable1615; This will produce the following output −+-----------------------------------------+ | ListOfSubject                           | +-----------------------------------------+ | Python, Java, MySQL, MongoDB, C, ...

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