# SQL glossary

99 SQL terms, from Novice to Master. Start with the basics or jump to a level.

Updated: September 28, 2026

## Novice

- [ASC](https://www.ask-codey.com/glossary/asc): An ORDER BY direction that sorts from lower values to higher values.
- [BETWEEN Condition](https://www.ask-codey.com/glossary/between-condition): The BETWEEN condition is used in a WHERE clause to determine if a value is in a given…
- [CHECK Constraint](https://www.ask-codey.com/glossary/check-constraint): A constraint requiring inserted or updated rows to satisfy a search condition.
- [Column Alias](https://www.ask-codey.com/glossary/column-alias): A temporary output name assigned to a selected expression or column.
- [Comparison Predicate](https://www.ask-codey.com/glossary/comparison-predicate): A condition comparing values with operators such as =, <>, <, or >=.
- [DEFAULT Clause](https://www.ask-codey.com/glossary/default-clause): A clause providing a value when an INSERT omits the column.
- [DESC](https://www.ask-codey.com/glossary/desc): An ORDER BY direction that sorts from higher values to lower values.
- [DISTINCT](https://www.ask-codey.com/glossary/distinct): A SELECT option that removes duplicate rows from a result.
- [FROM](https://www.ask-codey.com/glossary/from): A query clause identifying the source tables, views, or derived tables.
- [Logical Predicate](https://www.ask-codey.com/glossary/logical-predicate): A condition that combines or reverses other conditions with AND, OR, or NOT.
- [NOT NULL Constraint](https://www.ask-codey.com/glossary/not-null-constraint): A constraint requiring a column to contain a non-NULL value.
- [NULL](https://www.ask-codey.com/glossary/null-database): A marker indicating that a value is missing or unknown, rather than zero or an empty string.
- [Numeric Literal](https://www.ask-codey.com/glossary/numeric-literal): A number written directly in a SQL statement.
- [ORDER BY](https://www.ask-codey.com/glossary/order-by): A clause that sorts a query result by one or more expressions.
- [Query](https://www.ask-codey.com/glossary/query): A request for data or another result from a database.
- [Result Set](https://www.ask-codey.com/glossary/result-set): The rows and columns produced by a query.
- [SELECT](https://www.ask-codey.com/glossary/select-database): A statement or query clause that chooses expressions and columns for a result.
- [Snake Case](https://www.ask-codey.com/glossary/snake-case): All letters are lower case, each word is separated by an underscore.
- [SQL Statement](https://www.ask-codey.com/glossary/sql-statement): A complete SQL instruction sent to a database management system.
- [String Literal](https://www.ask-codey.com/glossary/string-literal): Text written between single quotation marks in SQL.
- [Structured Query Language (SQL)](https://www.ask-codey.com/glossary/structured-query-language-sql): The standardized language for defining, querying, and changing relational data.
- [UNIQUE Constraint](https://www.ask-codey.com/glossary/unique-constraint): A constraint preventing duplicate values or value combinations in specified columns.
- [WHERE](https://www.ask-codey.com/glossary/where-database): A query clause keeping only rows for which its condition is true.

## Apprentice

- [Aggregate Function](https://www.ask-codey.com/glossary/aggregate-function): A function that summarizes a set of rows into one value.
- [Aggregate Functions](https://www.ask-codey.com/glossary/aggregate-functions): Aggregate functions are SQL functions that reduce values in one or more rows into a…
- [ALTER TABLE](https://www.ask-codey.com/glossary/alter-table): A statement that changes the definition of an existing table.
- [Approximate Numeric Type](https://www.ask-codey.com/glossary/approximate-numeric-type): A floating-point numeric type that may store an approximation of a value.
- [AVG](https://www.ask-codey.com/glossary/avg): An aggregate function returning the average of non-NULL numeric values.
- [BETWEEN Predicate](https://www.ask-codey.com/glossary/between-predicate): A predicate testing whether a value falls within an inclusive lower and upper bound.
- [CASE Expression](https://www.ask-codey.com/glossary/case-expression): An expression that chooses a result by evaluating conditions in order.
- [Character String Type](https://www.ask-codey.com/glossary/character-string-type): A SQL type whose values are sequences of characters.
- [COUNT](https://www.ask-codey.com/glossary/count): An aggregate function returning the number of qualifying rows or non-NULL expression values.
- [CREATE TABLE](https://www.ask-codey.com/glossary/create-table): A statement that defines a new table, its columns, and its constraints.
- [CREATE VIEW](https://www.ask-codey.com/glossary/create-view): A statement that defines a view from a query.
- [CROSS JOIN](https://www.ask-codey.com/glossary/cross-join): A join returning every possible pairing of rows from two table expressions.
- [Data Control Language (DCL)](https://www.ask-codey.com/glossary/data-control-language-dcl): SQL statements that control database privileges and access.
- [Data Definition Language (DDL)](https://www.ask-codey.com/glossary/data-definition-language-ddl): SQL statements that define or change database structures.
- [Data Manipulation Language (DML)](https://www.ask-codey.com/glossary/data-manipulation-language-dml): SQL statements that retrieve or change stored rows.
- [Date and Time Type](https://www.ask-codey.com/glossary/date-and-time-type): A SQL type representing a date, time, timestamp, or interval.
- [DELETE](https://www.ask-codey.com/glossary/delete): A statement that removes selected rows from a table.
- [DROP TABLE](https://www.ask-codey.com/glossary/drop-table): A statement that removes a table definition and its stored data.
- [Exact Numeric Type](https://www.ask-codey.com/glossary/exact-numeric-type): A numeric type representing values with defined precision and scale without binary approximation.
- [EXCEPT](https://www.ask-codey.com/glossary/except): A set operation returning distinct rows in the first result but not the second.
- [EXISTS Predicate](https://www.ask-codey.com/glossary/exists-predicate): A predicate that is true when its subquery returns at least one row.
- [FETCH FIRST](https://www.ask-codey.com/glossary/fetch-first): A standard clause limiting a query result to its first specified number of rows.
- [FULL OUTER JOIN](https://www.ask-codey.com/glossary/full-outer-join): A join returning matched rows plus unmatched rows from both sides.
- [GROUP BY](https://www.ask-codey.com/glossary/group-by): A clause collecting rows with equal grouping values so each group produces one result row.
- [HAVING](https://www.ask-codey.com/glossary/having): A clause filtering groups after grouping and aggregation.
- [IN Predicate](https://www.ask-codey.com/glossary/in-predicate): A predicate testing whether a value equals any value in a list or subquery result.
- [INNER JOIN](https://www.ask-codey.com/glossary/inner-join): A join returning only row combinations that satisfy its join condition.
- [INSERT](https://www.ask-codey.com/glossary/insert): A statement that adds new rows to a table.
- [INTERSECT](https://www.ask-codey.com/glossary/intersect): A set operation returning distinct rows present in both query results.
- [IS NULL Predicate](https://www.ask-codey.com/glossary/is-null-predicate): A predicate testing whether a value is NULL.
- [JOIN](https://www.ask-codey.com/glossary/join-database): A query operation combining related rows from two table expressions.
- [Join Condition](https://www.ask-codey.com/glossary/join-condition): The predicate deciding which rows from joined sources match.
- [LEFT OUTER JOIN](https://www.ask-codey.com/glossary/left-outer-join): A join returning every left row and matching right rows, using NULLs when no right match exists.
- [LIKE Predicate](https://www.ask-codey.com/glossary/like-predicate): A predicate comparing text with a pattern containing wildcard characters.
- [MAX](https://www.ask-codey.com/glossary/max): An aggregate function returning the highest non-NULL value.
- [MIN](https://www.ask-codey.com/glossary/min): An aggregate function returning the lowest non-NULL value.
- [OFFSET Clause](https://www.ask-codey.com/glossary/offset-clause): A clause skipping a specified number of ordered result rows.
- [ON Clause](https://www.ask-codey.com/glossary/on-clause): A join clause containing its match condition.
- [RIGHT OUTER JOIN](https://www.ask-codey.com/glossary/right-outer-join): A join returning every right row and matching left rows, using NULLs when no left match exists.
- [Scalar Subquery](https://www.ask-codey.com/glossary/scalar-subquery): A subquery required to return one column and no more than one row.
- [Self Join](https://www.ask-codey.com/glossary/self-join): A query that joins a table to another reference to the same table.
- [SET Clause](https://www.ask-codey.com/glossary/set-clause): The UPDATE clause assigning new values to columns.
- [Set Operation](https://www.ask-codey.com/glossary/set-operation): An operation combining compatible query results according to set rules.
- [Subquery](https://www.ask-codey.com/glossary/subquery): A query nested inside another SQL statement.
- [SUM](https://www.ask-codey.com/glossary/sum-database): An aggregate function adding the non-NULL numeric values in a group.
- [Table Subquery](https://www.ask-codey.com/glossary/table-subquery): A subquery producing rows and columns that another query can use as a table.
- [Transaction Control Language (TCL)](https://www.ask-codey.com/glossary/transaction-control-language-tcl): SQL statements that complete, reverse, or mark points within transactions.
- [UNION](https://www.ask-codey.com/glossary/union): A set operation combining compatible query results and removing duplicate rows.
- [UNION ALL](https://www.ask-codey.com/glossary/union-all): A set operation combining compatible query results while retaining duplicate rows.
- [UPDATE](https://www.ask-codey.com/glossary/update): A statement that changes values in existing rows.
- [VALUES Clause](https://www.ask-codey.com/glossary/values-clause): A clause that supplies rows of literal or calculated values.
- [Wildcard Character](https://www.ask-codey.com/glossary/wildcard-character): A pattern character representing unknown text, such as % or \_ with LIKE.

## Journeyman

- [Alias](https://www.ask-codey.com/glossary/alias): An Alias is an alternate (usually short) name assigned to a table to make it easier to…
- [COMMIT](https://www.ask-codey.com/glossary/commit): A statement that successfully ends a transaction and makes its changes durable.
- [Common Table Expression (CTE)](https://www.ask-codey.com/glossary/common-table-expression-cte): A named query expression introduced by WITH for use within one statement.
- [Correlated Subquery](https://www.ask-codey.com/glossary/correlated-subquery): A subquery that refers to values from an outer query and is evaluated in that context.
- [DENSE_RANK](https://www.ask-codey.com/glossary/dense-rank): A window function assigning equal rank to peers without leaving gaps after ties.
- [LAG](https://www.ask-codey.com/glossary/lag): A window function returning a value from an earlier row in the window partition.
- [LEAD](https://www.ask-codey.com/glossary/lead): A window function returning a value from a later row in the window partition.
- [OVER Clause](https://www.ask-codey.com/glossary/over-clause): The clause defining the row window used by a window function.
- [PARTITION BY](https://www.ask-codey.com/glossary/partition-by): An OVER subclause dividing query rows into independent window-function groups.
- [RANK](https://www.ask-codey.com/glossary/rank): A window function assigning equal rank to peers and leaving gaps after ties.
- [READ COMMITTED](https://www.ask-codey.com/glossary/read-committed): An isolation level preventing a statement from reading uncommitted changes.
- [READ UNCOMMITTED](https://www.ask-codey.com/glossary/read-uncommitted): The isolation level allowing the broadest concurrency and permitting dirty reads.
- [Recursive CTE](https://www.ask-codey.com/glossary/recursive-cte): A CTE that repeatedly refers to its own accumulated result until no new rows are produced.
- [REPEATABLE READ](https://www.ask-codey.com/glossary/repeatable-read): An isolation level preventing reread rows from changing during the transaction.
- [ROLLBACK](https://www.ask-codey.com/glossary/rollback): A statement that reverses a transaction's uncommitted changes.
- [ROW_NUMBER](https://www.ask-codey.com/glossary/row-number): A window function assigning consecutive numbers to rows within each window partition.
- [SAVEPOINT](https://www.ask-codey.com/glossary/savepoint): A named point inside a transaction to which later work can be rolled back.
- [SERIALIZABLE](https://www.ask-codey.com/glossary/serializable): The strongest standard isolation level, requiring results consistent with some serial order.
- [Window Frame](https://www.ask-codey.com/glossary/window-frame): The subset of rows around the current row used by a window function.
- [Window Function](https://www.ask-codey.com/glossary/window-function): A function calculating across related rows without collapsing them into one row per group.

## Freelancer

- [Deferrable Constraint](https://www.ask-codey.com/glossary/deferrable-constraint): A constraint whose checking may be postponed until transaction completion.
- [Initially Deferred](https://www.ask-codey.com/glossary/initially-deferred): A constraint mode starting each transaction with checking postponed until commit.
- [Initially Immediate](https://www.ask-codey.com/glossary/initially-immediate): A constraint mode starting each transaction with checking performed after each statement.

## Master

- [Natural Join](https://www.ask-codey.com/glossary/natural-join): A join matching equally named columns automatically and returning one copy of each matched column.

[More subjects in Databases](https://www.ask-codey.com/glossary/groups/databases)

Source: https://www.ask-codey.com/glossary/subjects/sql