General
SQL is an abbreviation of
Structured query language
Write an SQL query to find the current date-time
SELECT NOW()
This join selects all rows from both participating tables as long as there is a match between the columns.
Inner Join
This statement is often used with aggregate functions ( COUNT() , MAX() , MIN() , SUM() , AVG() ) to group the result-set by one or more columns.
Group By
A FIXED length string (can contain letters, numbers, and special characters).
Char
SQL views are also known as
Virtual tables
SQL query to view timezone
SHOW timezone()
This join returns all (matched or unmatched) rows from the tables on both sides of the join clause.
Full Outer Join
This clause was added to SQL because the WHERE keyword cannot be used with aggregate functions.
Having
Zero is considered as false, nonzero values are considered as true.
Bool
How many primary keys can you have in a table?
Only 1
SQL query to view today's date
SELECT CURRENT_TIME()
This join returns all records from the left table (table1), and the matching records from the right table (table2).
Left Join
This statement in sql is used to sort the fetched data in either ascending or descending according to one or more columns.
Order By
Allows whole numbers between -2,147,483,648 and 2,147,483,647
int
What is the difference between a PRIMARY KEY and a UNIQUE KEY?
We can have only one primary key in a table while we can have multiple unique keys
SQL query to know , what is the time now.
SELECT CURRENT_TIME
This join returns all the rows of the table on the right side of the join and matching rows for the table on the left side of join.
Right Join
It specifies a limited number of rows in the result set to be returned based on number of rows
Limit
Fixed precision and scale numbers.
numeric
When is a WHERE clause is useful?
For giving conditions
SQL query to show the time as text
SELECT TIMEOFDAY()
This operator combines the result sets of two different queries. Column data types in the two queries must match.
Union
This operator selects values within a given range.
Between
Monetary data
money