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MS SQL Server – Insert, Update & Delete

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In Microsoft SQL Server, “Insert,” “Update,” and “Delete” are essential SQL statements that allow you to manage data within database tables.

  1. INSERT:
    • The INSERT statement is used to add new records (rows) to a database table.
    • You specify the table name and the values you want to insert into each column in the new row.
    • Here’s a basic example of an INSERT statement:INSERT INTO Customers (CustomerName, ContactName, City) VALUES ('Example Company', 'John Doe', 'New York');
    • This query inserts a new customer record into the “Customers” table with the specified values.
  2. UPDATE:
    • The UPDATE statement is used to modify existing records in a database table.
    • You specify the table name, the columns to update, and the new values for those columns, along with a WHERE clause to specify which rows to update.
    • Here’s a basic example of an UPDATE statement:UPDATE Products SET Price = 19.99 WHERE Category = 'Electronics';
    • This query updates the “Price” column of all products in the “Products” table with the category ‘Electronics’ to a new price of 19.99.
  3. DELETE:
    • The DELETE statement is used to remove records from a database table.
    • You specify the table name and use a WHERE clause to specify which rows to delete.
    • Here’s a basic example of a DELETE statement:DELETE FROM Orders WHERE OrderDate < '2023-01-01';
    • This query deletes all orders from the “Orders” table that were placed before January 1, 2023.
  4. Transactions:
    • In SQL Server, it’s common to perform multiple INSERT, UPDATE, or DELETE operations as part of a single transaction. Transactions ensure that a group of operations either all succeed or all fail, maintaining data consistency.
  5. Data Integrity:
    • When using these statements, it’s crucial to consider data integrity constraints, such as primary keys, foreign keys, and unique constraints, to ensure the integrity of your data.
  6. Logging and Performance:
    • These operations are logged, and SQL Server provides mechanisms like transaction logs for data recovery and auditing.
    • Performance can be optimized through appropriate indexing and query optimization techniques, especially for large datasets.

Insert, update, and delete operations are fundamental for maintaining and manipulating data in SQL Server databases. Properly using these statements in combination with transactions and data integrity constraints ensures the reliability and consistency of your database.