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14 Cards in this Set
- Front
- Back
Data manipulation language (DML) |
command used by users to query and maintain existing data EX. SELECT, INSERT, UPDATE, DELETE |
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Data definition language (DDL) |
used by developers to maintain databases EX. CREATE, ALTER, DROP |
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Data control language (DCL) |
commands used by administrators to control database security and access. ex. GRANT, REVOKE |
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PRIMARY KEY |
unique Identifier |
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Composite key |
consists of more than one attribute to uniquely identify an entity occurrence. Used for creating intersection tables. Syntax in sql is
CONSTRAINT alias_name PRIMARY KEY (animal_id, anotherpk_ID); |
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DEFAULT Field |
gives the field a default value. Syntax
name varchar(35) DEFAULT 'FLEA'); |
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foreign key |
is a field (or collection of fields) in one table that uniquely identifies a row of another table. 1] In a simpler words, a foreign key is defined in the second table, which is referring the primary key of the first table. Shown as an underlined value in tables. |
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cascade |
type of foreign key constraint. Deleting or updating the value in the parent able automatically deletes or update the value in the child table. |
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Restrict |
rejects the delete or update operation in the parent table (default option in sql). |
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Set null |
deleting or updating the value in parent table sets the value in the child table to null. |
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DROP TABLE |
drops a table, and if the table has a child may delete depending on constraints. |
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INSERT |
inserts data into tables (character and date fields must be within single quotes.) |
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DELETE |
deletes specific records in a table; |
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TRUNCATE |
deletes all rows of a table |