Top 10 BASIC SQL Concepts useful for Database Testing
1. SELECT and FROM: This is the “heart” of any SQL query - SELECT columns FROM table.
2. WHERE: This acts as a filter and allows you to select only relevant rows based on conditions.
3. GROUP BY: This helps you aggregate the data by grouping columns.
4. AVG/SUM/MAX/MIN: These are aggregate functions that help you summarise the data.
5. COUNT and DISTINCT: Count helps you find the number of entries and Distinct helps you find unique entries.
6. CASE WHEN: This is a very useful way to create a new derived field or perform complex aggregate operations.
7. JOIN: Join helps you combine data from different tables using join conditions. Please get familiar with inner and left/right/full outer joins.
8. UNION: Union and Union All help you to combine data from multiple tables with similar structure.
9. WINDOW FUNCTION: Allow you to perform calculations across a set of rows.
10. CTE and SUBQUERY: They help you create more complex queries by combining smaller queries.
Happy Learning!😇😇😇
