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A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
To discover such errors, one must perform a query that uses a left outer join between the table with the foreign key and the table with the primary key, showing both key fields in addition to any fields required to distinguish the record; all invalid foreign-key values will have the primary-key column as NULL. The need to perform such a check ...
A commonly used CREATE command is the CREATE TABLE command. The typical usage is: CREATE TABLE [table name] ( [column definitions]) [table parameters] The column definitions are: A comma-separated list consisting of any of the following; Column definition: [column name] [data type] {NULL | NOT NULL} {column options} Primary key definition ...
AJAX/JavaScript-driven web interface for PostgreSQL. Allows browsing, maintaining and creating data and database objects via a web browser. The interface offers tabbed SQL editor with autocompletion, row editing widgets, click-through foreign key navigation between rows and tables, favorites management for commonly used scripts, among other ...
Using a database-specific stored procedure that generates the surrogate key, performs the INSERT operation, and finally returns the generated key. For example, in Microsoft SQL Server, the key is retrieved via the SCOPE_IDENTITY() special function, while in SQLite the function is named last_insert_rowid().
Create/alter table: Yes - can create table, alter its definition and data, and add new rows; Some - can only create/alter table definition, not data; Browse table: Yes - can browse table definition and data; Some - can only browse table definition; Multi-server support: Yes - can manage from the same window/session multiple servers
The primary key is a column, or a set of columns, that is used to uniquely identify each row. An example might be Product ID or Order ID. Set up the table relationships – Look at each table and decide how the data in one table is related to the data in other tables. Add fields to tables or create new tables to clarify the relationships, as ...
Between multiple tables circular constraints (e.g. foreign keys) are permitted by defining the constraints as deferrable (See CREATE TABLE for PostgreSQL and DEFERRABLE Constraint Examples for Oracle). In that case the constraint is checked at the end of the transaction not at the time the DML statement is executed.