Found 6702 Articles for Database

Can we perform MySQL UPDATE and change nothing in a table?

AmitDiwan
Updated on 27-Sep-2019 07:55:11

300 Views

Yes, we can do that. Let us first create a table −mysql> create table DemoTable(    Id int ); Query OK, 0 rows affected (1.02 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(201); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values(202); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values(290); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(301); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+------+ ... Read More

What does select @@identity do in MySQL?

AmitDiwan
Updated on 27-Sep-2019 07:53:46

1K+ Views

The @@identity returns the last inserted value in the auto_increment column in the current session. Let us first create a table −mysql> create table DemoTable(    UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    UserName varchar(100) ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(UserName) values('David'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(UserName) values('Mike'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(UserName) values('Carol'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(UserName) values('Robert'); Query OK, 1 row affected (0.24 sec) ... Read More

MySQL query to fetch the maximum corresponding value from duplicate column values

AmitDiwan
Updated on 27-Sep-2019 07:52:33

138 Views

Let us first create a table −mysql> create table DemoTable(    ProductName varchar(100),    ProductPrice int ); Query OK, 0 rows affected (0.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Product-1', 56); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Product-2', 78); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values('Product-1', 88); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Product-2', 86); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Product-1', 45); Query OK, 1 row affected (0.18 sec) mysql> insert into ... Read More

Will extending the size of a varchar field in MySQL affect the data inside it?

AmitDiwan
Updated on 27-Sep-2019 07:50:35

372 Views

If you will extend the size of a varchar field in MySQL then it won’t affect the data inside it.Let us first create a table −mysql> create table DemoTable(    Name varchar(8) ); Query OK, 0 rows affected (1.11 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Mike'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Sam'); Query OK, 1 row affected (0.13 sec)Display all records from the ... Read More

Sort a list in MySQL and display a fixed result at the end of the column?

AmitDiwan
Updated on 27-Sep-2019 07:48:52

55 Views

Let us first create a table −mysql> create table DemoTable(    FirstName varchar(100) ); Query OK, 0 rows affected (0.97 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.31 sec) mysql> insert into DemoTable values('Adam'); Query OK, 1 row affected (0.35 sec) mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Sam'); Query OK, 1 row affected (0.37 sec) mysql> insert into DemoTable values('Mike'); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected (0.27 ... Read More

Fetch random rows from a table with MySQL

AmitDiwan
Updated on 27-Sep-2019 07:47:30

106 Views

For this, you can use a PREPARE statement. Let us first create a table −mysql> create table DemoTable(    FirstName varchar(100),    CountryName varchar(100) ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Adam', 'US'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Chris', 'AUS'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Robert', 'UK'); Query OK, 1 row affected (0.32 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+-----------+-------------+ | FirstName | ... Read More

How to find repeated rows and display there count in a separate column with MySQL?

AmitDiwan
Updated on 27-Sep-2019 07:45:57

88 Views

For this, use the GROUP BY HAVING clause. Let us first create a table −mysql> create table DemoTable(    Name varchar(100),    Age int ); Query OK, 0 rows affected (1.50 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 23); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('David', 21); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Chris', 23); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Chris', 21); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable values('Mike', 25); Query OK, ... Read More

Check if a given year is leap year in PL/SQL

Arnab Chakraborty
Updated on 27-Sep-2019 07:46:15

2K+ Views

Here we will see how to check given year is leap year or not, using PL/SQL. In PL/SQL code, some group of commands are arranged within a block of related declaration of statements.The leap year checking algorithm is like below.AlgorithmisLeapYear(year): begin    if year is divisible by 4 and not divisible by 100, then       it is leap year    else if the number is divisible by 400, then       it is leap year    else       it is not leap year endExampleDECLARE    year NUMBER := 2012; BEGIN    IF MOD(year, 4)=0   ... Read More

Select with set order in MySQL

AmitDiwan
Updated on 27-Sep-2019 07:44:11

101 Views

For this, you need to use IN() and after that FIELD() method. Let us first create a table −mysql> create table DemoTable(    StudentId varchar(10),    StudentName varchar(20) ) ; Query OK, 0 rows affected (4.11 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('10001', 'Adam'); Query OK, 1 row affected (0.52 sec) mysql> insert into DemoTable values('1010', 'Chris'); Query OK, 1 row affected (0.72 sec) mysql> insert into DemoTable values('1020', 'Bob'); Query OK, 1 row affected (0.34 sec) mysql> insert into DemoTable values('1030', 'Carol'); Query OK, 1 row affected (0.47 sec) mysql> insert into ... Read More

How to search a column for an exact string in MySQL?

AmitDiwan
Updated on 27-Sep-2019 07:42:41

1K+ Views

For exact string, you need to use wildcard ‘%’ with LIKE operator −select *from yourTableName where binary yourColumnName LIKE '%yourStringValue%';Let us first create a table −mysql> create table DemoTable(    Name varchar(20) ); Query OK, 0 rows affected (1.93 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (1.11 sec) mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.38 sec) mysql> insert into DemoTable values('Adam'); Query OK, 1 row affected (1.19 sec) mysql> insert into DemoTable values('JOHN'); Query OK, 1 row affected (0.60 sec) mysql> insert into DemoTable ... Read More

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