Get Expertise in Database Testing(SQL) + Linux for Testers

Learn to fetch data with SQL select queries, choosing all columns or specific fields from tables like employees, with case-insensitive keywords and optional semicolon.

Master data filtration with the where clause in SQL by filtering rows using conditions on the employee number, office code, and job title.

Learn to filter data in SQL by applying the where clause with and/or across multiple columns, using office code, job title, and employee number as examples.

Learn to filter data with in and between in select queries, using a country list and a credit limit range, including not in and not between variations.

Learn how to fetch unique data from a column using select distinct and how to view a table's structure with describe or desc, illustrated on an employees table.

Use column aliases to rename results for presentation. Learn to combine first and last names with concat into a full name, and display employee code and phone extension.

Master SQL sorting with the order by clause to arrange results in ascending or descending order, including multi-column sorting, and understand where clause placement at the end of the query.

Explore pattern matching with the like operator to fetch data using wildcards in SQL, using percent and underscore to filter by starts with, ends with, and contains.

Master SQL pattern matching by using like with wildcards and underscore to filter customers by second character, second last character, and exact or minimum name lengths.

Learn how to write a sub query by placing a query inside another, using an inner query to compute an average and an outer query to fetch customers above average.

Learn to fetch null data with select queries, using is null and is not null, and distinguish null from zero or blank in customers and employees tables.

Learn to perform arithmetic on column data in SQL, adding, subtracting, multiplying, and dividing values like credit limit, and use aliases for computed columns such as new credit limit.

Explore how to delete data from tables using delete, truncate, and drop in SQL, showing conditional vs unconditional deletes, table preservation, and DML vs DDL concepts.

Explore group functions in SQL, including min, max, avg, sum, and count, applied to numeric columns like credit limit to produce a single result.

Learn how to group data with the group by clause, counting by country, office code, or job title, and compute max and average credit limits.

Learn to filter data before group by with where, filter groups after group by with having, and combine both in a single sql query for accurate averages by country.

Explore how to fetch data from multiple tables using SQL joins, including inner, left, right, full outer, cross (cartesian) joins, and self joins, with practical examples.

Demonstrates cross join (Cartesian join) by merging every row from one table with every row from another table, highlighting two-table combinations with practical SQL examples.

Explore inner join concepts, equi join, and simple joins by merging two tables on a matching office code to fetch employee and location data.

Explore left outer join by merging two tables on a condition, returning all records from the left table plus matching right-side data, with nulls where no match exists.

Explore right outer join concepts by merging two tables, returning matching records and right-side-only rows, with practical examples using employees and offices in SQL.

Master the full outer join by using a union of left outer join and right outer join to display all records from both tables, including nonmatching rows.

Learn how to perform a self join, an inner join on a single table, by using aliases to display an employee name alongside their manager name.

Create new tables by copying a table's structure and data. Copy only the structure for a blank template, or use selective data and columns.

Create a new table by defining its structure, including id and employee_name columns, then set primary key, not null, and default values, and describe the table.

Learn how to insert complete and partial data into a table, handle primary keys and null values and defaults, and use column lists for flexible data insertion.

Master updating table data using conditional and unconditional update queries with set and where clauses, and understand primary key and not null constraints, and how updates may affect multiple rows.

Use alter queries to update table structure with adding, dropping, renaming, and resizing columns, applying not null and primary key constraints, and adjust column order and data types.

Explore SQL views as virtual tables derived from a select statement that do not store data. Use views to restrict columns for security and simplify access to underlying data.

Speed up search statements with indexes, not visible to users, by guiding queries to relevant rows; create a country index on customers and maintain it for inserts, updates, and deletes.

Learn how union and union all combine results from two select statements in SQL, requiring the same number of columns, and how duplicates are handled.

Explains the not null constraint in SQL, showing how to enforce non-null values on a column when creating or altering a table, with examples for id, employee name, and salary.

Apply a check constraint to enforce data rules on a column, such as salary must be greater than 10,000, allowing inserts only when the condition passes.

Explore how a default constraint assigns a predefined value to a column when no value is provided, illustrated using an employee table with a default for name.

Enforce data uniqueness with the unique constraint on one or more columns, allow nulls, and prevent duplicates during inserts with practical table creation and examples.