Results for “SQL”
Small, practical examples. Search by task or narrow things down below.
Read updated base-table values through a view
Postgres: An ordinary view reflects later changes to its underlying data.
Postgres✓ Tested
Read values from an inserted row
Use RETURNING to retrieve an automatically assigned row ID.
RETURNING✓ Tested
Read values generated by INSERT
Capture an IDENTITY value with OUTPUT.
OUTPUT✓ Tested
Reference a parent identified by two columns
Postgres: A composite foreign key checks the complete referenced key rather than either column independently.
Postgres✓ Tested
Reject a negative quantity with CHECK
Postgres: Combine NOT NULL and CHECK because an unknown NULL check result is normally accepted.
Postgres✓ Tested
Reject duplicate business identifiers
Postgres: A UNIQUE constraint protects a business key independently of the primary key.
Postgres✓ Tested
Remove dependent rows with a declared cascade
Postgres: ON DELETE CASCADE removes children when their referenced parent is deleted.
Postgres✓ Tested
Remove duplicate result values
Postgres: Use DISTINCT when repeated category values are not useful.
Postgres✓ Tested
Remove duplicate values while keeping the smallest key
Postgres: Identify retained keys in a grouped subquery before deleting other copies.
Postgres✓ Tested
Remove surrounding spaces from text
Postgres: TRIM removes leading and trailing space characters by default.
Postgres✓ Tested
Repeat the first ordered value beside each row
Postgres: FIRST_VALUE reads the first value in the current window frame.
Postgres✓ Tested
Replace a literal substring
Postgres: REPLACE performs a literal replacement rather than a regular-expression substitution.
Postgres✓ Tested