MySQL Articles - Page 159 of 355

To update an existing table, use UPDATE. With that, to set the current date, use the CURDATE() method −update yourTableName set yourCoumnName=CURDATE();Let us first create a table −mysql> create table DemoTable -> ( -> DueDate datetime -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-01-10') ; Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('2019-03-31'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+---------------------+ | DueDate ... Read More

Use SUBSTRING_INDEX to select everything before @ in an email-id −select substring_index(yourColumnName, '@', 1) from yourTableName;Let us first create a table −mysql> create table DemoTable -> ( -> EmployeeMailId varchar(100) -> ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Larry123@gmail.com'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('987Sam@hotmail.com'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('123456David_98@gmail.com'); Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the ... Read More

To set default field value, use the “default”. Let us first create a table −mysql> create table DemoTable -> ( -> Age int -> ); Query OK, 0 rows affected (0.58 sec)Here is the query to set default field value in MySQL −mysql> alter table DemoTable MODIFY Age int default 18; Query OK, 0 rows affected (0.25 sec) Records: 0 Duplicates: 0 Warnings: 0Now you can check the table description −mysql> desc DemoTable;OutputThis will produce the following output −+-------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+---------+------+-----+---------+-------+ | Age ... Read More

Let us first create a table −mysql> create table DemoTable -> ( -> Amount int, -> SubTotal int -> ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command −ysql> insert into DemoTable(Amount) values(50); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Amount) values(60); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(Amount) values(70); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(Amount) values(80); Query OK, 1 row affected (0.17 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce ... Read More

Since “select” is a reserved word in MySQL, we cannot create a table name with it. But, if you still want to create such a table, surround the word select with quote.Let us first create a table −mysql> create table `select` -> ( -> Number int -> ); Query OK, 0 rows affected (0.79 sec)Insert some records in the table using insert command −mysql> insert into `select` values(10); Query OK, 1 row affected (0.16 sec) mysql> insert into `select` values(20); Query OK, 1 row affected (0.11 sec) mysql> insert into `select` values(30); Query OK, 1 row affected (0.12 ... Read More

Let us first see the syntax of IF NOT IN in MySQL −if(yourVariableName  NOT IN (yourValue1, yourValue2, ........N) ) then    statement1 else    statement2 endif    Let us implement the above syntax to use IF NOT IN −mysql> DELIMITER // mysql> CREATE PROCEDURE IF_NOT_INDemo(IN value int)    ->    BEGIN    ->       if(value NOT IN  (10, 20, 30) ) then    ->          select "Value Not Found";    ->       else    ->          select "Value Found";    ->       end if;    ->    END ... Read More

Let us first create a table −mysql> create table DemoTable    -> (    -> UserId int    -> ); Query OK, 0 rows affected (0.48 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(20); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.09 sec) ... Read More

For this, you can use ORDER BY DESC LIMIT. Let us first create a table −mysql> create table DemoTable    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(100)    -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('John'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(Name) values('Sam'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(Name) values('Carol'); Query OK, 1 row affected (0.34 sec)Display all records from the table using select statement −mysql> ... Read More

Yes, the AUTO_INCREMENT in MySQL will be signed (Positive and Negative Value both) by default.Let us first create a table −mysql> create table DemoTable    -> (    -> MyNumber int AUTO_INCREMENT PRIMARY KEY    -> ); Query OK, 0 rows affected (0.45 sec)Insert some records in the table using insert command. Here, we have set negative values as well for AUTO_INCREMENT column −mysql> insert into DemoTable values() ; Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(-100); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(-300); Query OK, 1 row affected ... Read More

To order an alphanumeric column with values like “100X, “2Z”, etc. use the ORDER BY. Let us first create a table −mysql> create table DemoTable -> ( -> StudentId varchar(100) -> ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2X'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('100Y'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('100X'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('2Z'); Query OK, 1 row affected (0.14 sec) mysql> ... Read More