SQL Server 2008 R2: Multiple Conditions on the Same Column with AND Operator

Introduction

In this article, we will explore how to apply multiple conditions on the same column in SQL Server 2008 R2 using the AND operator. We will also discuss the different methods available to achieve this and provide examples of each.

Understanding SQL Server 2008 R2

Before diving into the topic at hand, it is essential to understand the basics of SQL Server 2008 R2. This includes knowledge of basic SQL concepts such as SELECT, FROM, WHERE, AND, OR, GROUP BY, HAVING, and JOIN.

SQL Server 2008 R2 is a relational database management system that supports various data types and operations. It uses a hierarchical structure to organize data, with tables and rows forming the core of the database.

Table Creation

To begin with, we need to create a table called EMPDetails with four columns: ID, EmpName, ColumnName, and ColumnValue.

CREATE TABLE EMPDetails (
    ID int,
    EmpName varchar(20),
    ColumnName varchar(20),
    ColumnValue varchar(20)
);

Inserting Records

Next, we need to insert some records into the table. These records will contain various combinations of values for the ID, EmpName, ColumnName, and ColumnValue columns.

INSERT INTO EMPDetails Values(1,'S','Company','Microsoft');
INSERT INTO EMPDetails Values(1,'S','Profession','Database');
INSERT INTO EMPDetails Values(1,'S','Location','USA');
INSERT INTO EMPDetails Values(1,'S','Company','Unisys');
INSERT INTO EMPDetails Values(1,'S','Company','TATA');

INSERT INTO EMPDetails Values(2,'U','Company','Microsoft');
INSERT INTO EMPDetails Values(2,'U','Profession','Software');
INSERT INTO EMPDetails Values(2,'U','Location','UK');
INSERT INTO EMPDetails Values(2,'U','Company','DXC');
INSERT INTO EMPDetails Values(2,'U','Company','AOL');

INSERT INTO EMPDetails Values(3,'R','Company','Microsoft');
INSERT INTO EMPDetails Values(3,'R','Profession','Software');
INSERT INTO EMPDetails Values(3,'R','Location','UK');
INSERT INTO EMPDetails Values(3,'R','Company','AOL');

Querying the Table

Now that we have inserted records into the table, let’s query it using a SELECT statement. We want to select all columns from the table where the ColumnName is ‘Company’ and the ColumnValue is ‘Microsoft’. However, this condition alone does not meet our requirements because we also need to filter for another column.

Using AND Operator

To apply multiple conditions on the same column using the AND operator, we can use a subquery in the WHERE clause of the main query. The subquery will contain all possible combinations of ColumnName and ColumnValue that satisfy both conditions.

SELECT  a.*
FROM    EMPDetails a
        INNER JOIN
        (
            SELECT  ID, EmpName
            FROM    EMPDetails
            WHERE   (ColumnName = 'Company' AND ColumnValue = 'Microsoft') OR
                    (ColumnName = 'Profession' AND ColumnValue = 'Software')
            GROUP   BY ID, EmpName
            HAVING  COUNT(*) = 2
        ) b ON a.ID = b.ID
                AND a.EmpName = b.EmpName
WHERE (a.ColumnName = 'Company'    AND a.ColumnValue = 'Microsoft') OR
      (a.ColumnName = 'Profession' AND a.ColumnValue = 'Software')

In this query, the subquery groups the records by ID and EmpName, and applies both conditions using GROUP BY and HAVING clauses. The main query then joins this subquery with the EMPDetails table on the ID and EmpName columns.

Explaining the Query

The query works as follows:

1. Subquery: The subquery selects all unique combinations of ColumnName and ColumnValue that satisfy both conditions.

   • (ColumnName = 'Company' AND ColumnValue = 'Microsoft') OR (ColumnName = 'Profession' AND ColumnValue = 'Software')
   • GROUP BY ID, EmpName groups the records by ID and EmpName based on this condition.
   • HAVING COUNT(*) = 2 filters out any records that do not meet both conditions exactly twice.

2. Main Query: The main query joins this subquery with the EMPDetails table on the ID and EmpName columns using an INNER JOIN.

3. Filtering Conditions: Finally, the main query applies a filter to select only rows where a.ColumnName = 'Company' AND a.ColumnValue = 'Microsoft' or a.ColumnName = 'Profession' AND a.ColumnValue = 'Software'. This ensures that we are selecting both records that meet our requirements and any additional columns from the EMPDetails table.

Conclusion

In this article, we explored how to apply multiple conditions on the same column in SQL Server 2008 R2 using the AND operator. We discussed various methods for achieving this, including the use of subqueries, GROUP BY, HAVING, and JOIN clauses. By understanding these concepts and applying them effectively, you can improve your database queries and become more efficient at retrieving data from your databases.

Additional Resources

For further learning, here are some additional resources:

• SQL Tutorial for Beginners: This tutorial covers the basics of SQL and provides an introduction to various concepts.
• Database Management Systems: This article discusses the different types of database management systems and their applications.

Last modified on 2025-02-26