Missing Data
When we don't have all the information needed to model data, we often use NULL. However, that causes other issues.
2021-04-12
2,806 reads
Joe Celko
Mathematicians and SQL
Georg Ferdinand Ludwig Philipp Cantor is considered the creator of set theory, and his theories are the basis for the naïve set theory you learned in school. But there are lots of other mathematicians you should know, such as Hilbert, Frege, Russell, Zermelo and Dedekind. They made a lot of contributions, too. Hilbert Hilbert is […]
2021-01-19
5,679 reads
Data Element Names and Scoping Rules in SQL
How you name data elements in databases and applications programs has often been a matter of personal taste. Decades ago, when I worked for state government, there is a COBOL programmer who would pick a theme for his programs. The paragraphs and variables would be named based on the current theme. One of his programs […]
2021-01-11
2,211 reads
Stairway to Database Design Level 8: Cursors
This final level to the first landing completes the basics of a SQL database, by explaining what cursors are and why you should never use them.
2020-11-18 (first published: 2011-11-02)
11,827 reads
2020-10-12
2,022 reads
Stairway to Data, Level 4: Temporal Data
Joe Celko tackles the most difficult of all the types of data handled by SQL, temporal data, and explains how to avoid the commonest traps for the unwary programmer
2020-07-08 (first published: 2011-06-15)
11,307 reads
Stairway to Database Design Level 6: Procedure Bodies
Having covered the procedure headers in SQL Server in the previous level, Joe tackles the subject of the contents of stored procedures. In this level, he outlines limitations of TSQL as a procedural language, and what you need to bear in mind when deciding how to use them.
2019-04-03 (first published: 2011-09-21)
13,614 reads
Stairway to Data, Level 1: The Basics
A great deal of the confusion that occurs when a database application is developed comes from a poor understanding of the basics of data. Here, Joe Celko gives a broad coverage of the difficulties you're likely to meet when handling data in databases.
2019-02-06 (first published: 2011-05-12)
20,801 reads
Stairway to Database Design Level 9: Normalization
In the final step of Database Design, Joe Celko gives a simple but effective explanation of the normalization process and why it is important.
2018-02-21 (first published: 2011-11-11)
15,790 reads
Stairway to Database Design Level 7: Triggers
In levels one to four, we built the tables, base and virtual, of a schema. Levels five and six dealt with stored procedures. This level deals with a feature you need to avoid as much as possible; this is article is on Triggers.
2018-01-24 (first published: 2011-09-30)
12,473 reads
Blogs
Measuring RAG Solutions: Are We Retrieving the Right Information?
A RAG pipeline that answers questions in the demo is not the same thing...
Advice I Like: Lots of Ideas
By Steve Jones
“A multitude of bad ideas is necessary for one good idea” – from Excellent...
Building a DBA Agent for Your SQL Server Estate with MCP
Yesterday I gave a talk for MSSQLTips called “Building a DBA Agent for Your...
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Question of the Day
Adding new column with DEFAULT
Which number will the COUNT() return after executing the following statements:
DROP TABLE IF EXISTS #test; CREATE TABLE #test (id INT) INSERT INTO #test (id) SELECT * FROM GENERATE_SERIES(1, 3) AS gs ; ALTER TABLE #test ADD flag BIT CONSTRAINT DF_#test_flag DEFAULT 0; go UPDATE #test SET flag = 0 WHERE id = 1 UPDATE #test SET flag = 1 WHERE id = 2 INSERT INTO #test (id) VALUES (4) SELECT COUNT(*) FROM #test AS t WHERE flag = 0See possible answers
