Database Fundamentals #16: Removing Data With T-SQL

Database Fundamentals
Deleting data from a table using T-SQL works quite a lot like the UPDATE statement. How it Works In the same way you supply the statement, DELETE, and then the table name. You’re not going to specify columns in any way because deleting data is all about removing a row. If you just wanted to remove the values in a column, you would use the UPDATE statement. Because of this, the only other thing you need for a DELETE statement is the WHERE clause. Just like with the UPDATE statement, if you don’t supply a WHERE clause, then the DELETE statement will remove all data in the table. Be very careful about using this statement. Make sure you’ve always got a WHERE clause. This example would delete all the rows…
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Database Fundamentals #15: Modifying Data With T-SQL

Database Fundamentals, SQL Server 2005, SQL Server 2008, SQL Server 2012, SQL Server 2014, SQL Server 2016, SQL Server 2017
The preferred method for modifying your data within a database is T-SQL. While the last Fundamentals post showed how to use the GUI to get that done, it's not a very efficient mechanism. T-SQL is efficient. UPDATE The command for updating information in your tables is UPDATE. This command doesn’t work the same way as the INSERT statement. Instead of listing all the columns that are required, meaning columns that don’t allow for NULL values, you can pick and choose the individual columns that you want to update. The operation over-writes the information that was stored in the column with new information. In addition to defining the table and columns you want to update, you have to tell SQL Server which rows you’re interested in updating. This introduces the WHERE…
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Database Fundamentals #14: Modifying Data Through SSMS

Database Fundamentals
I've said it before, but I feel I should repeat myself. Using the SSMS GUI for data entry and data manipulation is not the preferred mechanism. T-SQL is the right way to manipulate the data in your database. For purposes of completion though, I will show the GUI methods in this blog series. Information doesn’t go into the database and stay there, unchanged, forever. Data is modified. This occurs because information changes, such as when a person marries and changes their name, or information was incorrectly entered, in which case you need to fix it, or just about anything else. You have to have a mechanism for modifying existing information. Modifying Data You start modifying data in the tables the same way you did the insert, by taking advantage of…
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