Basics of Sql

Section 1. Querying data

This section helps you learn how to query data from the SQL Server database. We will start with a simple query that allows you to retrieve data from a single table.

SELECT– show you how to query data against a single table.

Section 2. Sorting data

ORDER BY– sort the result set based on values in a specified list of columns . you can learn more on sql certification

Section 3. Limiting rows

OFFSET FETCH – limit the number of rows returned by a query.
SELECT TOP– limit the number of rows or percentage of rows returned in a query’s result set.

Section 4. Filtering data

DISTINCT– select distinct values in one or more columns of a table.
WHERE– filter rows in the output of a query based on one or more conditions.
AND – combine two Boolean expressions and return true if all expressions are true.
OR– combine two Boolean expressions and return true if either of conditions is true.
IN – check whether a value matches any value in a list or a subquery.
BETWEEN – test if a value is between a range of values.
LIKE – check if a character string matches a specified pattern.
Column & table aliases – show you how to use column aliases to change the heading of the query output and table alias to improve the readability of a query.

Section 5. Joining tables

Joins – give you a brief overview of joins types in SQL Server including inner join, left join, right join and full outer join.
INNER JOIN – select rows from a table that have matching rows in another table.
LEFT JOIN – return all rows from the left table and matching rows from the right table. In case the right table does not have the matching rows, use null values for the column values from the right table.
RIGHT JOIN – learn a reversed version of the left join.
FULL OUTER JOIN – return matching rows from both left and right tables, and rows from each side if no matching rows exist.
CROSS JOIN – join multiple unrelated tables and create Cartesian products of rows in the joined tables.
Self join – show you how to use the self-join to query hierarchical data and compare rows within the same table. become an expert in sql through sql online training

Section 6. Grouping data

GROUP BY– group the query result based on the values in a specified list of column expressions.
HAVING – specify a search condition for a group or an aggregate.
GROUPING SETS – generates multiple grouping sets.
CUBE – generate grouping sets with all combinations of the dimension columns.
ROLLUP – generate grouping sets with an assumption of the hierarchy between input columns.

Section 7. Subquery

This section deals with the subquery which is a query nested within another statement such as SELECT, INSERT, UPDATE or DELETE statement.

Subquery – explain the subquery concept and show you how to use various subquery type to select data.
Correlated subquery – introduce you to the correlated subquery concept.
EXISTS – test for the existence of rows returned by a subquery.
ANY – compare a value with a single-column set of values returned by a subquery and return TRUE the value matches any value in the set. prepare on pl sql interview questions
ALL – compare a value with a single-column set of values returned by a subquery and return TRUE the value matches all values in the set.

Section 8. Set Operators

This section walks you through of using the set operators including union, intersect, and except to combine multiple result sets from the input queries.

UNION – combine the result sets of two or more queries into a single result set.
INTERSECT – return the intersection of the result sets of two or more queries.
EXCEPT – find the difference between the two result sets of two input queries.