Easy way to fix SQL checksum string

August 27, 2020 by Jimmie Bourn

 

Over the past few weeks, some of our users have encountered a known SQL checksum string error code. This problem can arise for several reasons. Let's discuss some of them below.

SQL Server Rider Used to detect random errors in data transfer. An algorithm is usually used to calculate the checksum value, and each algorithm is designed for a specific purpose. This hash function is used to calculate a checksum value for an entire row or list of expressions or columns.

 

 



There are times when we need to compare two tables and see if the dates are the same. I often see several ways to do this. Most of them are quite slow and inefficient. I would like to present a quick and slightly messy approach using the CHECKSUM and CHECKSUM_AGG functions.


How do I find previous rows in SQL?

In other words, the LAG () function allows you to access the data of the previous line, or the line before the previous line, etc. from the current line. The LAG () function can be very useful for comparing the value of the current row with the value of the previous row.


With these two functions, it is very easy to compare data in two tables. We need to create a checksum for the entire table. This can be done simply by first generating a checksum for each row and then specifying the aggregated checksum for the table using CHECKSUM_AGG ().


How do I sum a row in SQL?

SELECT department, SUM (sales) AS "total sales" FROM order_details GROUP BY department; Since you have specified a column in your SQL SELECT statement that is not wrapped in the SQL SUM function, you must use the SQL GROUP BY clause. Therefore, the department field must be listed in the SQL GROUP BY clause.


Above, a checksum is returned for all data in the table. Do this on two or more tables. If the checksums match, you know the data in these tables match.


What is a row SQL?

In the context of a relational database, a row, also known as a tuple, represents one element of implicitly structured data in a table. Simply put, a database table can be thought of as consisting of rows and columns. Each column expects a data value of a specific type.


For some reason, I have two copies of tables in the Undercover catalog database that I want to view.


checksum sql row

So, from the above we can see that the data in the two tables is the same. For reflection, let's try to delete a row from the table and see what happens with the checksum.



Remember the above phash collision problem, although the risk is very low. I can do a little research for CHECKSUM and hash collisions in a future post and see how productive they actually are.

 

 

 

 

 

 

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