Here is an example to use SQL variable in the mysql select query like clause
SET @name = 'advancewebsoftware';
SELECT * from `user` WHERE name LIKE CONCAT('%', @name, '%');Hope this help!
Category: Sql Server
MySQL : The host localhost does not support SSL connections
When I moved database MySql.Data 7.0.7 to 8.0.8. I got following error
The host localhost does not support SSL connections.
So, here is the solution for this error ,Just add SslMode=none in connection string
server=localhost;user id=roor;password=xyz;persistsecurityinfo=True;port=123;database=TestDB; SslMode=none
Hope it helps !
SQL : Paging in Stored Procedure
Create simple Student table using following script
CREATE TABLE [dbo].[Student]( [ID] [int] NOT NULL, [Name] [varchar](50) NOT NULL) ON [PRIMARY]GO
The OFFSET-FETCH clause is used to fetch specif records. OFFSET-FETCH can be used only with the ORDER BY clause.
Stored Procedure :
Limitations in Using OFFSET-FETCH
- ORDER BY is mandatory to use OFFSET and FETCH clause.
- OFFSET clause is mandatory with FETCH. You can never use, ORDER BY … FETCH.
- TOP cannot be combined with OFFSET and FETCH in the same query expression.
- The OFFSET/FETCH rowcount expression can be any arithmetic, constant, or parameter expression that will return an integer value. The rowcount expression does not support scalar sub-queries.
MYSQL : How to skip first 10 records from a SELECT query and take next 10?
We know there are skip and take operators available in linq to skip and take
The Take operator is used to return a given number of rows from a object list and the Skip operator skips over a specified number of rows in object list.
var employee = (from emp in employeeContext.EMPLOYEEs
where emp.SALARY < 1300
select emp).Skip(2).Take(5);
Is there a way in MySQL to achieve the same like have the first 10 result from a SELECT query skipped and select next 10?
Answer : Yes we can use LIMIT with two parameter
Introduction to MySQL LIMIT clause
The LIMIT clause is used in the SELECT statement to constrain the number of rows in a result set. The LIMIT clause accepts one or two arguments. The values of both arguments must be zero or positive integers.
The following illustrates the LIMIT clause syntax with two arguments:
SELECT * FROM table LIMIT offset , count;
Let’s examine the LIMIT clause parameters:
- The
offsetspecifies the offset of the first row to return. Theoffsetof the first row is 0, not 1. - The
countspecifies the maximum number of rows to return.
When you use the LIMIT clause with one argument, this argument will be used to determine the maximum number of rows to return from the beginning of the result set.
SELECT * FROM table LIMIT count;
Use LIMIT with two parameters. For example, to return results 11-60 (where result 1 is the first row), use:
SELECT * FROM foo LIMIT 10, 50Hope this help !
Get Row Number in MySQL
SQL Server
To return a row number with record we have ROW_NUMBER() in SQL which returns the sequential number of a row within a partition of a result set, starting at 1 for the first row in each partition.
Syntax:
ROW_NUMBER ( )
OVER ( [ PARTITION BY value_expression , … [ n ] ] order_by_clause )
MY SQL
Here I am explaining how to return row number in my sql
For Example we have following table
CREATE TABLE tblSales( id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, fruit VARCHAR(32), amount DECIMAL ); INSERT INTO tblSales VALUES (NULL, 'apple', 12.75), (NULL, 'orange', 1.89), (NULL, 'pear', 19.23), (NULL, 'banana', 4.25), (NULL, 'cherry', 123.75), (NULL, 'plum', 23.15);
SELECT fruit, amount FROM tblSales ORDER BY amount DESC; If we run this query it will result like +--------+--------+ | fruit | amount | +--------+--------+ | cherry | 124 | | plum | 23 | | pear | 19 | | apple | 13 | | banana | 4 | | orange | 2 | +--------+--------+
Now here is the query with ranking SET @rank=0; SELECT @rank:=@rank+1 AS rank, fruit, amount FROM tblSales ORDER BY amount DESC; +------+--------+--------+ | rank | fruit | amount | +------+--------+--------+ | 1 | cherry | 124 | | 2 | plum | 23 | | 3 | pear | 19 | | 4 | apple | 13 | | 5 | banana | 4 | | 6 | orange | 2 | +------+--------+--------+
Hope it helps!
Age calculation in mysql Select query
Following is the way to calculate age based on date in mysql select query
SELECT name, birth, CURDATE(),TIMESTAMPDIFF(YEAR,birth,CURDATE()) AS ageFROM TableName;+----------+------------+------------+------+ | name | birth | CURDATE() | age | +----------+------------+------------+------+ | Fluffy | 1993-02-04 | 2003-08-19 | 10 | | Claws | 1994-03-17 | 2003-08-19 | 9 | | Buffy | 1989-05-13 | 2003-08-19 | 14 | | Fang | 1990-08-27 | 2003-08-19 | 12 | | Bowser | 1989-08-31 | 2003-08-19 | 13 | | Chirpy | 1998-09-11 | 2003-08-19 | 4 | | Whistler | 1997-12-09 | 2003-08-19 | 5 | | Slim | 1996-04-29 | 2003-08-19 | 7 | | Puffball | 1999-03-30 | 2003-08-19 | 4 | +----------+------------+------------+------+ Hope this is helpful !
Function to find dates in current week in mysql
MySQL YEARWEEK() returns year and week number for a given date.
Syntax: YEARWEEK(date_value,Mode)
Parameters or Arguments
- date_value
- A date or datetime value from which to extract the year and week.
- mode
- Optional. It is used to specify what day the week starts on. It can be one of the following:
mode Explanation Week Value 0 First day of the week is Sunday 0-53 1 First day of the week is Monday and the first week has more than 3 days 0-53 2 First day of the week is Sunday 1-53 3 First day of the week is Monday and the first week has more than 3 days 1-53 4 First day of the week is Sunday and the first week has more than 3 days 0-53 5 First day of the week is Monday 0-53 6 First day of the week is Sunday and the first week has more than 3 days 1-53 7 First day of the week is Monday 1-53
Example : select YEARWEEK(now());
The following statement will return the year and week number of the date 2016-05-19.
SELECT YEARWEEK(‘2016-05-19’);
Hope this help!
SQL: Condition in Count()
Condition in count()
SELECT
count(case when EventTypeID =1 then 1 else null end) as TotalTournamentsAttended,
count(case when EventTypeID =2 then 1 else null end) as TotalLeaguesAttended
FROM
[Tables]
Difference Between Primary Key and Unique Key
| PRIMARY KEY | UNIQUE KEY | |
| NULL | It doesn’t allow Null values. Because of this we refer PRIMARY KEY = UNIQUE KEY + Not Null CONSTRAINT |
Allows Null value. But only one Null value. |
| INDEX | By default it adds a clustered index | By default it adds a UNIQUE non-clustered index |
| LIMIT | A table can have only one PRIMARY KEY Column[s] | A table can have more than one UNIQUE Key Column[s] |
| CREATE SYNTAX | Below is the sample example for defining a single column as a PRIMARY KEY column while creating a table:CREATE TABLE dbo.Customer ( Id INT NOT NULL PRIMARY KEY, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(50) )Below is the Sample example for defining multiple columns as PRIMARY KEY. It also shows how we can give name for the PRIMARY KEY: CREATE TABLE dbo.Customer |
Below is the sample example for defining a single column as a UNIQUE KEY column while creating a table:CREATE TABLE dbo.Customer ( Id INT NOT NULL UNIQUE, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(50) )Below is the Sample example for defining multiple columns as UNIQUE KEY. It also shows how we can give name for the UNIQUE KEY: CREATE TABLE dbo.Customer |
| ALTER SYNTAX | Below is the Syntax for adding PRIMARY KEY CONSTRAINT on a column when the table is already created and doesn’t have any primary key:ALTER TABLE dbo.Customer ADD CONSTRAINT PK_CUSTOMER PRIMARY KEY (Id) |
Below is the Syntax for adding UNIQUE KEY CONSTRAINT on a column when the table is already created:ALTER TABLE dbo.Customer ADD CONSTRAINT UK_CUSTOMER UNIQUE(Id) |
| DROP SYNTAX | Below is the Syntax for dropping a PRIMARY KEY:ALTER TABLE dbo.Customer DROP CONSTRAINT PK_CUSTOMER |
Below is the Syntax for dropping a UNIQUE KEY:ALTER TABLE dbo.Customer DROP CONSTRAINT UK_CUSTOMER |
MySQL : coalesce in mysql
DESCRIPTION
The MySQL COALESCE function returns the first non-null expression in the list.
SYNTAX
The syntax for the MySQL COALESCE function is:
COALESCE( expression1, expression2, ... expression_n ) e.g. SELECT COALESCE(t.col,1) FROM Table t Above query will return 1 if t.col is null. Hope this help !
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