Product articles SQL Prompt SQL Code Analysis

Problems with adding NOT NULL columns or making nullable columns NOT NULL (EI028)

Phil Factor explains the problems you might encounter when adding a non-nullable column to an existing table or altering a column that contains NULL values to be non-nullable. He demos a migration script that can deploy such changes safely. You might also learn that in an archaic form of the Scots language, used in Cumberland, the number 17 is "tiny bumfit"; I think the tiny bumfit bus goes from Penrith to Carlisle. Read more

The Sins of SELECT * (BP005)

If Prompt warns you of use of the asterisk, or 'star' (*), in SELECT statements, consider replacing it with an explicit column list. It will prevent unnecessary network load and query performance problems, and avoid problems if the column order changes, when inserting into a table. Read more

Using a Variable-length Datatype Without Explicit Length: The Whys and Wherefores (BP007/8)

If you declare a variable-length string , or coerce a string, without specifying its length, you can fall foul of ‘silent’ string truncation. Some developers resort to using the (MAX) specification, which is a mistake too. Phil Factor explains the dangers and then offers a workaround for the problem, when you're importing text and simply don't know the correct length of each string. Read more

The risks of using EXECUTE (‘SQL Script’)

SQL Prompt’s code analysis rule, BP013, will alert you to use of Execute(string) to execute a batch in a string, often assembled dynamically from user input. This technique is dangerous because the parameter values are injected before the statement is parsed by SQL Server, allowing an attacker to "tag on" extra statements. Use sp_ExecuteSql instead, and validate the string inputs. Read more

When to use the SELECT…INTO statement (PE003)

SELECT…INTO is a useful shortcut for development work, especially for creating temporary tables. However, it no longer has a clear performance advantage and should be avoided in production code. It is better to use a CREATE TABLE statement, where you can specify constraints and datatypes in advance, making it less likely that inconsistencies will sneak into the data. Read more