Found 6702 Articles for Database

Adding a column whose value is not null by default in MySQL?

Ankith Reddy
Updated on 30-Jul-2019 22:30:25

843 Views

For this, you need to remove the default keyword. The syntax is as follows:ALTER TABLE yourTableName ADD COLUMN yourColumnName dataType NOT NULL AFTER yourColumnName;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table AddingColumnDefaultValueNOTNULL    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> FirstName varchar(20),    -> LastName varchar(20),    -> Age int,    -> Address varchar(100),    -> Salary int,    -> PRIMARY KEY(Id)    -> ); Query OK, 0 rows affected (0.58 sec)Now check the description of table. The query is as follows:mysql> desc ... Read More

Reset MySQL field to default value?

George John
Updated on 30-Jul-2019 22:30:25

1K+ Views

In MySQL, there are two approaches by which you can reset the MySQL field to default value. One is default keyword and another is default() function.Case 1: Using default keyword. The syntax is as follows:UPDATE yourTableName SET yourColumnName=default where yourCondition;Case 2: Using default() function. The syntax is as follows:UPDATE yourTableName SET yourColumnName=default(yourColumnName) where yourCondition;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table Default_Demo    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> Name varchar(20),    -> Age int,    -> Salary float,    -> PRIMARY ... Read More

Can we select row by DATEPART() in MySQL? Is it possible?

Chandu yadav
Updated on 30-Jul-2019 22:30:25

2K+ Views

There is no DATEPART() function in MySQL, you need to use MONTH() function to extract the month name from date column. The syntax is as follows:SELECT *FROM yourTableName WHERE MONTH(yourDateColumnName)=yourValue;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table SelectRowFromDatePart -> ( -> Id int NOT NULL AUTO_INCREMENT, -> LoginDate date, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (2.42 sec)Now you can insert some records in the table using ... Read More

How to add the JDBC MySQL driver to an Eclipse project?

Arjun Thakur
Updated on 30-Jul-2019 22:30:25

9K+ Views

To add the JDBC MySQL driver to an Eclipse project, you need to follow the below steps.The first step is as follows:Step1: Create a dynamic web project with some name in Eclipse.Step2: After pressing the Dynamic Web Project, a new window will open. Now give the project name. The screenshot is as follows:After clicking the Finish button, you will get a project structure. The screenshot is as follows:Therefore, I have a project name JDBCJarFiles and in WEB-INF, there is a lib folder. You can add JDBC jar files in lib folder. Now, paste the jar files here. The screenshot is as ... Read More

Implement MySQL INSERT MAX()+1?

Ankith Reddy
Updated on 30-Jul-2019 22:30:25

1K+ Views

You need to use COALESCE() function for this. The syntax is as follows:INSERT INTO yourTableName(yourColumnName1, yourColumnName2) SELECT 1 + COALESCE((SELECT MAX(yourColumnName1) FROM yourTableName WHERE yourColumnName2=’yourValue’), 0), ’yourValue’;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table InsertMaxPlus1Demo    -> (    -> Id int,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (1.27 sec)Now you can insert some records in the table using insert command. The query is as follows:mysql> insert into InsertMaxPlus1Demo(Id, Name) values(1, 'John'); Query OK, 1 row affected (0.12 sec) mysql> insert ... Read More

MySQL case-insensitive DISTINCT?

George John
Updated on 30-Jul-2019 22:30:25

5K+ Views

If you want case-insensitive distinct, you need to use UPPER() or LOWER().Case 1: Using UPPER().The syntax is as follows:SELECT DISTINCT UPPER(yourColumnName) FROM yourTableName;Case 2: Using LOWER().The syntax is as follows:SELECT DISTINCT LOWER(yourColumnName) FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table CaseInsensitiveDistinctDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserEmailId varchar(30), -> UserPassword varchar(10), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.64 sec)Now you ... Read More

Run SQL file in MySQL database from terminal?

Arjun Thakur
Updated on 30-Jul-2019 22:30:25

6K+ Views

To run SQL file in database, you need to use below syntax:mysql -u yourUserName -p yourDatabaseName < yourFileName.sqlTo understand the above syntax, let us open command prompt using windows+R shortcut key.The snapshot is as follows:After pressing OK button, you will get a command prompt. The snapshot is as follows:Now reach the bin directory, the snapshot is as follows:Here is my file ‘mydb.sql’ which is located in bin directory. The snapshot and content of SQL file is as follows:Now you can type the above syntax which I have discussed to run SQL file. The snapshot of command is as follows:Now you ... Read More

Get another order after limit with MySQL?

Arjun Thakur
Updated on 30-Jul-2019 22:30:25

201 Views

You need to use subquery with select statement, one select for inner and one for outer. The inner select will return rows and outer will order by ascending order. The syntax is as follows:SELECT *FROM (    SELECT *FROM yourTableName ORDER BY yourColumnName1 DESC LIMIT 9 ) AS anyAliasName ORDER BY yourColumnName2;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table OrderByAfterLimit    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> UserName varchar(20),    -> UserAge int,    -> PRIMARY KEY(Id)    -> ); Query OK, ... Read More

Populating a table from query results in MySQL?

Ankith Reddy
Updated on 30-Jul-2019 22:30:24

434 Views

To populate a table from query results, use the following syntax:INSERT yourTableName(yourColumnName1, yourColumnName2, yourColumnName3, ..........N) SELECT yourColumnName1, yourColumnName2, yourColumnName3, ..........N FROM yourAnotherTableName;To understand the above syntax, let us create a table. The first table is as follows with some records. The query to create a table is as follows:mysql> create table PopulateTableDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> Name varchar(20),    -> Amount int,    -> ArrivalDateTime datetime,    -> PRIMARY KEY(Id)    -> ); Query OK, 0 rows affected (0.68 sec)Now you can insert some records in the table using insert command. The ... Read More

How to log in as a different user on MySQL?

George John
Updated on 30-Jun-2020 13:10:49

15K+ Views

If you want to login as a different user on MySQL, you need to use “mysql -u -p command”. The syntax is as follows to login as a different user.>mysql -u yourUsername -p After pressing enter key Enter password −To understand the above syntax, let us create a user in MySQL. The syntax is as follows −CREATE USER 'yourUserName'@'localhost' IDENTIFIED BY 'yourPassword';Now I am going to create a user with name ‘John’ and password is ‘john123456’. The query is as follows −mysql> CREATE USER 'John'@'localhost' IDENTIFIED BY 'john123456'; Query OK, 0 rows affected (0.15 sec)Now check the user has been ... Read More

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