Learn how to concatenate multiple rows into a single string in SQL Server using STRING_AGG and FOR XML PATH methods. Complete guide with examples for modern and legacy versions.
Learn how to find and remove duplicate records in SQL using multiple fields like email and name. Complete guide with examples for duplicate identification and cleanup.
Learn multiple methods to update SQL Server tables using SELECT statements. Master UPDATE with JOIN, subqueries, MERGE, and cursor-based updates with practical examples.
Learn the most efficient method to calculate total minutes between two time values in SQL Server using DATEDIFF function. Discover optimized approaches for better performance and accuracy.
Learn the most efficient method to calculate total minutes between two time values in SQL Server using DATEDIFF() function. Discover why it's better than manual calculations and handle edge cases properly.
Learn the key differences between INNER JOIN and OUTER JOIN in SQL. Discover how LEFT, RIGHT, and FULL OUTER JOINs work with practical examples and visual comparisons.
Learn efficient methods to retrieve the last record in each group in MySQL. Explore window functions, self-JOINs, and subquery approaches with performance comparisons for optimal database queries.
Learn the crucial differences between UNION and UNION ALL in SQL. Discover how UNION removes duplicates while UNION ALL preserves all rows, impacting performance and result size. Complete guide for SQL developers.