For example: SELECT TOP(5) contact_id, last_name, first_name FROM contacts WHERE last_name = 'Anderson' ORDER BY contact_id; This SQL SELECT TOP example would select the first 5 records from the contacts table where the last_name is 'Anderson'.
Why is symbol used in SQL?
The @CustID means it's a parameter that you will supply a value for later in your code. This is the best way of protecting against SQL injection. Create your query using parameters, rather than concatenating strings and variables.
What does != Mean in SQL?
Not Equal Operator: != Evaluates both SQL expressions and returns 1 if they are not equal and 0 if they are equal, or NULL if either expression is NULL.
What is #tablename in SQL?
#mytable is a temporary table where as mytable is a concrete table. You can read more about Temporary Tables in SQL Server. They are used most often to provide workspace for the intermediate results when processing data within a batch or procedure.Aug 2, 2012
How do you SELECT two tables in a single query?
To retrieve information from more than one table, you need to join those tables together. This can be done using JOIN methods, or you can use a second SELECT statement inside your main SELECT query—a subquery.Dec 6, 2019
How do I query 3 tables in SQL?
https://www.youtube.com/watch?v=TGt2xa7EzvI
How does SELECT distinct work?
A SELECT DISTINCT statement first builds our overall result set with all records, i.e including duplicate values based on FROM, JOIN, WHERE, HAVING, etc statements. Next, it sorts the result set based on the column_name or field with which DISTINCT has been used.
What is the difference between SELECT and SELECT distinct?
The DISTINCT keyword in SQL is used with the SELECT statement. By using SELECT immediately followed by the DISTINCT keyword, all the duplicate rows are removed from the result set. Check out our interactive SQL Practice Set course! Let's see an example of DISTINCT in action.
How do I use distinct in a single column in SQL?
Adding the DISTINCT keyword to a SELECT query causes it to return only unique values for the specified column list so that duplicate rows are removed from the result set. Since DISTINCT operates on all of the fields in SELECT's column list, it can't be applied to an individual field that are part of a larger group.