Adventures in Machine Learning

Mastering the SQL Server EXCEPT Operator: Definition Syntax and Examples

Introduction to SQL Server EXCEPT Operator

SQL Server is a database management system that uses SQL (Structured Query Language) to manage relational databases efficiently. SQL Server EXCEPT operator is one of the advanced features that SQL provides to SQL Server developers.

The EXCEPT operator allows developers to compare two sets of attributes and get the difference between them. It is quite similar to the UNION operator, but instead of combining two sets, it compares them.

In this article, we will discuss everything about SQL Server EXCEPT operator, including its definition, syntax, and examples.

Definition of SQL Server EXCEPT Operator

The SQL Server EXCEPT operator is used to return all the records from one query that are not present in another query. It returns the difference between two sets in the form of a new table.

The resulting table consists of columns and rows that are not present in the second query. It is essential to note that the two sets being compared must have the same number of columns, and the columns should have the same data types.

Syntax and Rules of SQL Server EXCEPT Operator

The syntax for the SQL Server EXCEPT operator is as follows:

SELECT column1, column2, column3, …

FROM table1

EXCEPT

SELECT column1, column2, column3, … FROM table2;

The above syntax shows that we are selecting columns from table1 and excluding the records that are present in table2.

The rules for the SQL Server EXCEPT operator are as follows:

1. The two tables should have the same number of columns.

2. The column names should be the same.

3. The data types of the columns should be the same.

SQL Server EXCEPT Operator Example

Simple EXCEPT Example

Let’s consider the following two tables:

Table 1 (A):

| ID | Name | Age |

| — | ——- | — |

| 1 | Ryan | 24 |

| 2 | John | 30 |

| 3 | Rachel | 22 |

Table 2 (B):

| ID | Name | Age |

| — | ——- | — |

| 1 | Ryan | 24 |

| 3 | Rachel | 22 |

If we wish to get the records present in Table 1 (A) but not in Table 2 (B), we can use the EXCEPT operator as follows:

SELECT *

FROM A

EXCEPT

SELECT *

FROM B;

The output of the above query will be:

| ID | Name | Age |

| — | —— | — |

| 2 | John | 30 |

The output shows that the record for John in Table 1 (A) is present, but it is not present in Table 2 (B).

EXCEPT with ORDER BY Example

In this example, we will apply the SQL Server EXCEPT operator on two tables and order the resulting output. Consider the following two tables:

Table 3:

| ID | CustomerName | Sales |

| — | ————–| —– |

| 1 | Microsoft | 1500 |

| 2 | Google | 1000 |

| 3 | Apple | 2000 |

Table 4:

| ID | CustomerName | Sales |

| — | ————–| —– |

| 1 | Microsoft | 1500 |

| 2 | Google | 1000 |

We will use the following query to get the difference between the tables:

SELECT *

FROM Table3

EXCEPT

SELECT *

FROM Table4

ORDER BY Sales DESC;

The output of the above query will be:

| ID | CustomerName | Sales |

| — | ————| ——|

| 3 | Apple | 2000 |

The output shows that the record for Apple is present only in Table 3 (with Sales = 2000) and is not present in Table 4. The records are ordered by their Sales value in descending order.

Conclusion

In this article, we discussed everything about SQL Server EXCEPT operator, including its definition, syntax, and examples. The EXCEPT operator is a powerful tool for developers who need to compare two sets of data efficiently.

It can help them to identify the differences between two tables and get the desired output. Using the examples provided in this article, developers can practice and use the EXCEPT operator in their SQL queries.

In this article, we explored the SQL Server EXCEPT operator, which allows developers to compare two sets of data and get the difference between them. We discussed its definition, syntax, and provided simple examples, including a more complex example that ordered the output.

The SQL Server EXCEPT operator is a powerful tool that can help developers to identify differences between two tables, and it is essential to understand its syntax and rules. We hope that the examples in this article have helped in understanding the importance of the EXCEPT operator and how it can be used in SQL queries.

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