Glossary

Aggregate Function
Performs an operation on a set of records in a column and returns a single value.
Arithmetic Operators
Arithmetic operators ARE: * (multiplication), / (division), DIV (integer division), % (MOD) or remainder, + (addition), - (subtraction). These operators can be used in the SELECT, WHERE, and ORDER BY clauses. Operators are evaluated in the same way as arithmetic in other contexts.
AVG function
Returns the average of the non-null columns in the expression.
BETWEEN operator
The BETWEEN operator is similar to >= and
CEILING function
Returns the next highest whole number no matter what the decimal point.
Column Aliases
A column alias provides a way to create a clean or more descriptive header for a results set. A column alias cannot be used in a SELECT, WHERE, GROUP BY or HAVING clause due to the order of execution. You must refer to the original column name.
Column Specifications
A column specification may be derived from a base table. Or it my be a calculated value as a result of an arithmetic expression or a function.
Comparison Operators
The comparison operators are = (equals), (greater than), =, (not equal), != (not equal). Comparison operators compare two expressions. The result of a comparison results to true or false. Comparison operators are not case sensitive and are used with text and dates as well as numbers.
Compound condition
When more than one logical operator (AND, OR, NOT) is used in the WHERE clause.
CONCAT function
Combines a list of strings into a single string.
COUNT function
The number of the non-null columns in the expression.
CURRENT_DATE function
Returns current local date.
CURRENT_TIME function
Returns current local time
DATE function
Extracts the date from date/time input. If time is included it is dropped.
DELETE clause
SQL clause that deletes data from a table.
DISTINCT clause
The DISTINCT clause removes duplicate rows from a query.
FLOOR function
Returns the next lowest whole number no matter what the decimal point.
FROM clause
Specifies the base table(s) from which results will be retrieved.
GROUP BY clause
Groups rows of a result set based on columns or expressions separated by commas.
HAVING clause
The HAVING CLAUSE allows you to use an aggregate function as a filter. This is not allowed in a WHERE clause.
IN operator
The IN operator tests whether an expression is equal to a value or values in a list of expressions. The order of the items in the list does not matter. You can use the NOT operator to test for items not in the list. The IN clause may be used with a subquery.
Indexes
A SQL index is like the index of a book. It speeds up the retrieval of a record. The relational database management system (RDBMS) can retrieve a record with the index key instead of having to perform a table scan.
INSERT clause
SQL Clause used to insert data into a table.
IS NULL function
Null values indicate an unknown or non-existent value and is different from an empty string (‘ ‘). To test for a null value you use the IS NULL clause. The test for a value use IS NOT NULL clause
JOIN (OUTER) clause
An outer join will return all the rows from one table and only the rows from the other table that match the join condition
JOIN clause
A JOIN clause allows you to access data from two or more tables in a query.
LEFT function
Returns a substring starting from the left side of the string.
LIKE operator
The LIKE keyword is used with the WHERE clause. The LIKE keyword and can use two symbols as wildcards. The percent ( % ) symbol matches any number of characters and the underscore ( _ ) matches a single character.
LIMIT clause
Specifies the number of rows to be returned.
Logical Operators: AND, OR, NOT
Logical operators are used in the WHERE clause You may use multiple logical operators in a WHERE clause to create a compound condition. The order of evaluation when multiple operators are used is shown in the table above.
LTRIM function
Removes leading spaces from a string.
MIN function
The lowest value off the non-null columns in the expression
NOW function
Returns current local date and time.
ORDER BY clause
SQL clause that orders a result set.
REGEXP operator
REGEXP operator allows you to do more complex pattern matching than a LIKE keyword/ Some version of REGEXP exists in many computer languages. Refer to the “LIKE and REGEXP” handout for a full list of examples.
RIGHT function
Returns a substring starting from the right side of the string.
ROUND function
Rounds to the decimal specified.
RTRIM function
Removes trailing spaces from a string.
SELECT clause
Specifies the columns that will appear in a SQL query result set.
Subquery
A subquery is a SELECT statement coded within another SELECT statement.
SUM function
The total of the non-null columns in the expression.
Summary Query
A query that uses at least one aggregate function.
TRIM function
Removes leading and trailing spaces from a string.
TRUNCATE function
Returns the number truncated to the precision specified.
UNION clause
A UNION combines the results of two or more queries into a single result set.
UPDATE clause
SQL clause that updates data in a table.
UTC_DATE function
Returns current UTC date.
UTC_time function
Returns current UTC time.
VIEWS
A SQL view is a SELECT statement that is stored as a database object.
WHERE function
Specifies any conditions for the results set (filter).
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