SQL Advanced | Wildcards
SQL Wildcard Examples We have the following “Persons” table: Using the % Wildcard Now we want to select the persons living in a city that starts with “sa” from the…
SQL | The BETWEEN Operator
BETWEEN Operator Example The “Persons” table: Now we want to select the persons with a last name alphabetically between “Hansen” and “Pettersen” from the table above. We use the following…
SQL | The IN Operator
The IN operator allows you to specify multiple values in a WHERE clause. SQL IN Syntax: IN Operator Example The “Persons” table: Now we want to select the persons with…
SQL | The INSERT INTO AND UPDATE Statement
The second form specifies both the column names and the values to be inserted: SQL INSERT INTO Example We have the following “Persons” table: Now we want to insert a…
SQL | Alias Operator
SQL Alias Syntax for Columns: Also read Alias Example Assume we have a table called “Persons” and another table called “Product_Orders”. We will give the table aliases of “p” and…
SQL | The LIKE Operator
SELECT column_name(s) FROM table_name WHERE column_name LIKE pattern LIKE Operator Example The “Persons” table: Now we want to select the persons living in a city that starts with “s” from…
SQL ADVANCE | The TOP Clause
SELECT TOP number|percent column_name(s) FROM table_name SQL SELECT TOP Equivalent in MySQL and Oracle: MySQL Syntax: SELECT column_name(s) FROM table_name LIMIT number Example: SELECT * FROM Persons LIMIT 5 Oracle…
SQL | The DELETE Statement
DELETE FROM table_name WHERE some_column=some_value Note: Notice the WHERE clause in the DELETE syntax. The WHERE clause specifies which record or records that should be deleted. If you omit the…
SQL The ORDER BY Keyword
SELECT column_name(s) FROM table_name ORDER BY column_name(s) ASC|DESC ORDER BY Example The “Persons” table: Now we want to select all the persons from the table above, however, we want to…
SQL WHERE Clause
The “Persons” table: Now we want to select only the persons living in the city “Sandnes” from the table above. We use the following SELECT statement using Where clause: The…
SQL Introduction
SQL is a standard language for accessing databases. How to use SQL to access and manipulate data in: MySQL, SQL Server, Access, Oracle, Sybase, DB2, and other database systems. SQL…
Pyspark Questions and Answers
Q1: Write pyspark code to create dataframe and print with ‘color’ and ‘weight’ as separate columns. inventoryData = schema = Product
Second or Third Highest Record in SQL
When data is given to us and we want to find out Top 3 or Bottom 5 records on the basis of some attribute, this can be easily solved by…
Tips For Writing Efficient And Faster SQL Queries
INTRODUCTION Query optimization is an important skill for SQL developers and database administrators (DBAs). In order to improve the performance of SQL queries, developers and DBAs need to understand the…