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SQL Server GROUP BY

The GROUP BY clause in SQL Server is used to arrange data into groups based on one or more columns. It is often used with aggregate functions like SUM, COUNT, AVG, MIN, and MAX to perform calculations on each group rather than on the entire dataset. The GROUP BY clause is especially useful when you […]

SQL Server WHERE

| SQL Server

The WHERE clause in SQL Server is a fundamental component of SQL queries used to filter records based on specified conditions. It allows users to retrieve only those rows from a table that meet the criteria defined in the query. By narrowing down results, the WHERE clause enhances efficiency and relevance in data retrieval. Key […]

SQL Server CHECK

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A CHECK constraint in SQL Server is a rule that enforces domain integrity by limiting the values that can be entered into a column or set of columns in a table. It ensures that the data stored in a column meets specific conditions, enhancing data accuracy and consistency. Key Features of a CHECK Constraint Validation […]

SQL Server UNIQUE

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The UNIQUE key constraint in SQL Server ensures that all values in a column or a combination of columns are distinct. It is used to prevent duplicate values in specified columns while allowing one NULL value per column in most cases (unlike the PRIMARY KEY constraint, which does not allow NULLs). Key Features of UNIQUE […]

SQL Server FOREIGN KEY

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In SQL Server, a FOREIGN KEY constraint is used to enforce referential integrity between two tables by establishing a relationship between a column (or a set of columns) in one table (child table) and the PRIMARY KEY or a UNIQUE key column(s) in another table (parent table). This ensures that values in the foreign key […]

SQL Server PRIMARY KEY

| SQL Server

When working with databases, ensuring data integrity and uniqueness is paramount. One of the most critical tools for achieving this in SQL Server is the PRIMARY KEY constraint. Whether you’re a beginner in database design or a seasoned professional, understanding how to use PRIMARY KEY effectively can make a significant difference in the performance, reliability, […]