Found 4219 Articles for MySQLi

Use the IS NOT NULL operator to compare with NULL values. The syntax is as follows −SELECT *FROM yourTableName where yourColumnName1 is not null or yourColumnName2 anyIntegerValue;To check the not equal to in presence of null, let us create a table. The query to create a table is as follows −mysql> create table IsNullDemo    −> (    −> ProductId int,    −> ProductName varchar(100),      −> ProductBackOrder int    −> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table with null value to avoid the presence of null. The query to insert records ... Read More

To get the first n characters of string with MySQL, use LEFT(). To get the last n char of string, the RIGHT() method is used in MySQL.The syntax for RIGHT() method is as follows −SELECT RIGHT(yourColumnName, valueOfN) as anyVariableName from yourTableName;To understand the above concept, let us create a table. The query to create a table is as follows −mysql> create table gettingLast5Characters    −> (    −> BookName varchar(100)    −> ); Query OK, 0 rows affected (0.73 sec)Now you can insert records in the table using insert command. The query is as follows −mysql> insert into gettingLast5Characters values('Introduction ... Read More

To get order by column and place empty records at the end, use ORDER By and “is null” from MySQL. The syntax is as follows −select *from yourTableName order by if(yourColumName = ’ ’ or yourColumName is null, 1, 0), yourColumnName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table emptyCellsAtEnd    −> (    −> ProductId varchar(100)    −> ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command. Some of these records are empty. The query is as follows −mysql> ... Read More

We will see here how to display all tables inside a MySQL database using Java. You can use show command from MySQL to get all tables inside a MySQL database.Let’s say our database is ‘test’. The Java code is as follows to show all table names inside a database ‘test’.The Java code is as follows. Here, connection is established between MySQL and Java −import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import com.mysql.jdbc.Connection; import com.mysql.jdbc.DatabaseMetaData; public class GetAllTables {    public static void main(String[] args) throws SQLException {       Connection conn = null;       try { ... Read More

You can bulk update MySQL data with one query using CASE command. The syntax is as follows −update yourTableName set yourUpdateColumnName = ( Case yourConditionColumnName WHEN Value1 THEN ‘’UpdatedValue’ WHEN Value2 THEN ‘UpdatedValue’ . . N END) where yourConditionColumnName IN(Value1, Value2, .....N);To understand the above concept, let us create a table. The query to create a table is as follows −mysql> create table UpdateAllDemo −> ( −> BookId int, −> BookName varchar(200) −> ); Query OK, 0 rows affected (1.18 sec)Insert some records in the table using insert ... Read More

To select domain name from email address, you can use in-built SUBSTRING_INDEX() function from MySQL.To understand the concept, let us create a table. The following is the query to create a table.mysql> create table selectDomainNameOnly −> ( −> UserEmailAddress varchar(200) −> ); Query OK, 0 rows affected (0.52 sec)Insert records in the table using insert command. The record will have email-ids from which we need to fetch the domain name. The query is as follows −mysql> insert into selectDomainNameOnly values('John123@yahoo.com'); Query OK, 1 row affected (0.10 sec) mysql> insert into selectDomainNameOnly ... Read More

Set column charset using character SET command. The syntax is as follows −ALTER TABLE yourTableName MODIFY youColumName type CHARACTER SET anyCharcaterSetName;You can use character set name utf8 or something elsE. To set column charset, let us first create a table. The query to create a table is as follows −mysql> create table setCharsetDemo −> ( −> FirstName varchar(60) −> ); Query OK, 0 rows affected (2.09 sec)Now you can check the current column character set with the help of show command. The query is as follows −mysql> show create table setCharsetDemo;The ... Read More

You can use aggregate function count() with group by. The syntax is as follows.select yourColumnName, count(*) as anyVariableName from yourtableName group by yourColumnName;To understand the above syntax, let us create a table. The query to create a table is as follows.mysql> create table CountSameValue -> ( -> Id int, -> Name varchar(100), -> Marks int -> ); Query OK, 0 rows affected (0.70 sec)Insert records in the table using insert command. The query is as follows.mysql> insert into CountSameValue values(1, 'Sam', 67); Query OK, 1 row affected (0.17 sec) mysql> insert into CountSameValue values(2, 'Mike', 87); Query OK, 1 ... Read More

To check for duplicates in MySQL, you can use group by having clause. The syntax is as follows.select yourColumnName1, yourColumnName2, ......N, count(*) as anyVariableName from yourTableName group by yourColumnName1, yourColumnName2 having count(*) > 1;To understand the above syntax, let us create a table. The query to create a table is as follows.mysql> create table DuplicateDemo -> ( -> StudentId int not null, -> StudentFirstName varchar(100), -> StudentLastName varchar(100), -> Primary Key(StudentId) -> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command. The query is as follows.mysql> insert into DuplicateDemo values(1, 'John', 'Smith'); Query ... Read More

You can use aggregate function sum() inside COALESCE(). The below syntax returns the sum of all if the record exists otherwise 0 is returned. The syntax is as follows.select COALESCE(sum(yourColumnName2), 0) AS anyVariableName from yourTableName where yourColumnName1 like '%yourValue%';To understand the above syntax, let us create a table. The query to create a table is as follows.mysql> create table SumDemo -> ( -> Words varchar(100), -> Counter int -> ); Query OK, 0 rows affected (0.93 sec)Insert some records in the table using insert command. The query is as follows.mysql> insert into SumDemo values('Are You There', 10); Query OK, 1 ... Read More