SQL Server is a powerful relational database management system that is widely used in the industry. In this article, we will discuss some important concepts and ideas related to SQL Server.

Table Aliases and Column Aliases

When dealing with long or complicated table and column names, aliases can be used to refer to them. For example, instead of writing “SELECT VeryLongColumnName col1 FROM VeryLongTableName tab1”, we can use aliases like “SELECT col1 FROM tab1”. These aliases do not affect the performance of the query.

Difference between CHAR and VARCHAR Datatypes

VARCHAR is a variable-length string datatype with a specified maximum length. If a string is shorter than the maximum length, it is stored without any extra characters. On the other hand, CHAR is a fixed-length string datatype with a specified set length. If a string is shorter than the set length, it is padded with extra characters. It is important to note that VARCHAR is more space-efficient than CHAR.

Difference between VARCHAR and VARCHAR(MAX) Datatypes

VARCHAR stores variable-length character data up to 8000 bytes, while VARCHAR(MAX) can store variable-length character data beyond 8000 bytes, up to 2 GB. The usage of VARCHAR(MAX) is recommended instead of the deprecated TEXT datatype.

Difference between VARCHAR and NVARCHAR Datatypes

VARCHAR and NVARCHAR are similar in functionality, but NVARCHAR can handle unicode characters, allowing for the storage of multiple languages in the database. However, NVARCHAR takes up twice as much space as VARCHAR. It is recommended to use NVARCHAR only when dealing with foreign languages.

Storing Multilanguage Data in a Table

When storing unicode data, there are two important points to note. First, the column must be of unicode data type (nchar, nvarchar, ntext). Second, the value must be prefixed with N while insertion. For example, “INSERT INTO table (Hindi_col) values (N’hindi data’)”.

Optimizing Stored Procedures

Stored procedure optimization is crucial for improving performance. Some tips and tricks include using the SET NOCOUNT ON statement, using schema name with object name, avoiding the prefix “sp_” in stored procedure names, using IF EXISTS (SELECT 1) instead of (SELECT *), using the sp_executesql stored procedure instead of EXECUTE statement, avoiding SQL Server cursors whenever possible, keeping transactions short, and using TRY-Catch for error handling.

Protecting Against SQL Injection Attack

SQL injection is a common attack where malicious code is inserted into strings that are later executed by SQL Server. To protect against SQL injection, it is important to use type-safe SQL parameters, parameterized input with stored procedures, the Parameters Collection with dynamic SQL, filtering input parameters, using the escape character in LIKE clause, and wrapping parameters with QUOTENAME() and REPLACE().

Finding Schema Name and Table Name for a Database

To find the schema name and table name for a database, you can use the following script:

SELECT '['+SCHEMA_NAME(schema_id)+'].['+name+']' AS SchemaTable
FROM sys.tables

Understanding the CHECKPOINT Process

The CHECKPOINT process in SQL Server writes all dirty pages (modified data pages in the buffer cache) for the current database to disk. This helps ensure data consistency and recovery in case of a system failure.

These are just a few concepts and ideas related to SQL Server. Understanding these concepts can help you become more proficient in working with SQL Server and optimizing your database performance.