In some situations, we need to get an overview of the data present in a table. Or perhaps we want to check if there are any duplicate values in the table that we do not want. How can we retrieve a list of such duplicate records using SQL script? How to Identify Duplicate Rows in… Read More »
What I have here today is a article for beginners. It will be full of sql query examples. We will start from the most basic ones and continue up. SQL queries will be organized chronologically according to their difficulty. I will add more later on. SQL knowledge is a must for any IT department nowadays.… Read More »
The error message “Conversion failed when converting the varchar value to data type int” occurs in SQL Server client (for example Management Studio) when attempting to convert a value stored as the varchar (text) data type to an integer data type. This might not be an issue if the varchar contains numeric values, but problems… Read More »
In one of our previous articles, we tried to see how to get data from Excel into an SQL table (Import Excel to SQL Database). Now, we will show you how to do the opposite – that is, how to get data from an SQL database into Excel – exporting a table. Generally, I don’t… Read More »
This mini-article is intended for beginners. We will take a closer look at how to write a simple T-SQL script, and I will also explain basic SQL commands. We will assemble the individual parts of the script step by step and explain their purpose as we proceed. Let’s dive into SQL basics in the following… Read More »
GROUP BY clause is used to group data. In most of the cases, we talk of a situation when we need to make an aggregate operation in the table (sum of sales, number of records, average, etc.) GROUP BY in SQL Script SELECT FROM WHERE GROUP BY HAVING ORDER BY Syntax SELECT [Column 1], [Column… Read More »
HAVING clause is a special type of SQL command. It works in a similar way as WHERE clause and we use it to define a condition. There are important differences between the two clauses. Let me explain the differences between SQL HAVING and WHERE. HAVING positioning in SQL script SELECT FROM WHERE GROUP BY HAVING… Read More »
ORDER BY clause in SQL enables us to sort results of the query by specific field (column) or more columns. There are 2 sorting options: Ascending order (ASC) – sorts records from lowest to highest in case of numbers and from A to Z in case of text strings Descending order (DESC) – sorts records… Read More »
WHERE clause is used to define limit requirements for queries. We are not interested in all records in most cases of queries into tables. Only some subsets of the records based on set criteria are of our interest. Order of WHERE Clause in SQL Script SELECT FROM WHERE GROUP BY HAVING ORDER BY Syntax SELECT… Read More »
When you work with SQL database you usually need more than 1 table. Some values are in one table and the others are in a different one = division of the information into many tables which are connected between each other (via keys) is the principle of relational database. There are 5 basic kinds of… Read More »