This command is used to select the distinct rows. For Example: If we want to select all distinct department names from employee table, the query would be: SELECT DISTINCT dept FROM employee;
MAX function is used to get the maximum value from a column. To get the maximum salary drawn by an employee, the query would be: SELECT MAX (salary) FROM employee;
A view is a virtual table which results of executing a pre-compiled query. A view is not part of the physical database schema, while the regular tables are.
A VIEW is a virtual table, through which a selective portion of the data from one or more tables can be seen. A view do not contain data of their own. They are used to restrict access to the database or to hide data complexity. A view is stored as a SELECT statement in the database. DML operations on a view like INSERT, UPDATE, DELETE affects the data in the original table upon which the view is based.
The Syntax to create a sql view is: CREATE VIEW view_name AS SELECT column_list FROM table_name [WHERE condition];
view_name is the name of the VIEW.
The SELECT statement is used to define the columns and rows that you want to display in the view.
SQL has several arithmetic functions to do math on the numbers, such as summing up, taking average, retrieved from the column. They are: AVG():- Average of the column COUNT():- Number of records MAX():- maximum of the column MIN():- minimum of the column SUM():- Sum of the column
INSTR Function:- The INSTR function in SQL is used to find the starting location of a pattern in a string. The syntax for the INSTR function is as follows: INSTR (str, pattern): Find the starting location of pattern in string str.
SUBSTR Function:- The Substring function in SQL is used to grab a portion of the stored data. The syntax for the SUBSTR function is as follows: SUBSTR(str,pos,len): Starting with the position pos in string str select the characters upto the length len.
In the above query, INSTR('abcabcabc', 'b') outputs 2 as the starting location of pattern
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