SQL Challenge: C-01


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SQL Day 11: Group By in SQL Server

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LO1: Grouping rows using Group By LO2: Filtering Groups LO3: Difference between Where and Having Clause Group By clause is used to group a selected set of rows into a set of summary rows by the values of one or more columns or expression. It is always used in conjunction with one or more aggregate functions. Let’s say we have a table tblEmployee which contains all the salary of employees including the cities. So if we need to find the maximum salary of employee we can use the MAX(Column_Name) aggregate function to find the highest salary of employees. select MAX(salary) from tblemployee In the same way, we can find the minimum salary and total salary of all the employees using different aggregate functions. select MIN(salary) as [Minimum Salary] from tblemployee select SUM(salary) as [Total Salary] from tblemployee Let’s say we have to find out the employee salary as per the different cities, to achieve this we need to use the Group B...
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SQL Day 3: Creating Tables & Enforcing Primary and Foreign Key

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LO1: Creating the Tables LO2: Enforcing Primary and Foreign Key Prerequisite: Creating a Database Creating Tables You can create a table by two ways. By Graphically : Expand the Database in Object Explorer and right click on Tables folder and click on New Table Give the Column Name, Data Type and check Allow Nulls. Column Name: This is going to be your column name and this column name should be unique in the table. Data Type: For which type of data will be contained in the column. For example int, nvarchar, float, image etc. Allow Nulls: This is a check box which tells us that the column will contain null values or not. Primary Key allows you to uniquely identify the row in the table and it does not allow null. Must Remember: Primary key can be applied to one single column or group of the column to uniquely identify a record/row in the table but only one primary key allows in the table. To make the primary key graphically y...
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SQL Day 17: Union and Union All

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LO1: Purpose of Union and Union All LO2: Difference between Union and Union All LO3: Difference between Joins and Union Prerequisite: Joins Union and Union All is used to combine the result set of two or more queries. To combine two results set, the column list in the select columns, data types, and order of the columns need to be same. Let’s say we have the two table tblcustomer1 and tblcustomer2 with the identical columns in each table. To combine these two result set into one we can use the Union All . select * from tblcustomer1 Union All select * from tblcustomer2 In the above screen, all the rows combined into one result set. Now let’s try to use the Union only and observe the result set. select * from tblcustomer1 Union select * from tblcustomer2 In the above screen, the duplicate row is included only once and the result also gets sorted. Note: In the case of Union, Duplicate rows only get removed from the re...
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