What is SQL ALL?

What is SQL ALL?

In SQL, the ALL keyword is used in the context of a comparison operator to indicate that all values in a set should be included in the comparison.

Examples

For example, the following query uses the > operator with the ALL keyword to find all customers who have made more purchases than all of the customers in the Customer table:

SELECT *
FROM Customer
WHERE TotalPurchases > ALL (SELECT TotalPurchases FROM Customer)

This query will return a list of all customers who have made more purchases than all other customers in the table.

Here is another example that uses the IN operator with the ALL keyword to find all customers who live in the same city as all other customers in the table:

SELECT *
FROM Customer
WHERE City IN ALL (SELECT City FROM Customer)

In this case, the query will return a list of all customers who live in the same city as every other customer in the table.

Here is one more example that uses the BETWEEN operator with the ALL keyword to find all customers who have made a certain number of purchases:

SELECT *
FROM Customer
WHERE TotalPurchases BETWEEN ALL (SELECT MinPurchases FROM Customer) AND ALL (SELECT MaxPurchases FROM Customer)

This query will return a list of all customers who have made a number of purchases that falls between the minimum and maximum number of purchases made by all customers in the table.

Does * mean all in SQL?

In SQL, the asterisk (*) is typically used as a wildcard to match zero or more characters in a string.

For example, the following query uses the asterisk wildcard to match all rows in a table where the LastName column starts with the letter "S":

SELECT *
FROM Customer
WHERE LastName LIKE 'S%'

For example, the following query uses the asterisk to select all columns from the Customer table:

SELECT *
FROM Customer

In this case, the asterisk is used to represent all columns in the table, rather than matching zero or more characters in a string.

Conclusion

In SQL, the ALL keyword is used in the context of a comparison operator to indicate that all values in a set should be included in the comparison.