CASE punika SQL conditional expression — ngeturnake nilai beda-beda adhedhasar kondisi, kaya if/else ing sajroning query. Digunakake ing SELECT (kolom computed/conditional), ORDER BY, aggregates, lan liyane — nambaake conditional logic menyang queries.
name,
age,
age
age
age_group
users;
Searched CASE nevaluasi kondisi ing urutane, ngeturnake nilai saka WHEN kapisan sing cocok. ELSE nyedhiyakake default (tanpa dheweke, baris sing ora cocok oleh NULL).
SELECT name,
CASE status -- simple form — compares `status` to each value
WHEN 'A' THEN 'Active'
WHEN 'I' THEN 'Inactive'
ELSE 'Unknown'
END AS status_label
FROM users;
-- count/sum conditionally (a very useful pattern)
SELECT
COUNT(CASE WHEN status = 'active' THEN 1 END) AS active_count,
COUNT(CASE WHEN status = 'inactive' THEN 1 END) AS inactive_count,
SUM(CASE WHEN type = 'sale' THEN amount ELSE 0 END) AS sales_total
FROM orders;
-- → multiple conditional counts/sums in ONE query (pivoting-like)
Nggunaaken CASE sajroning aggregates ninggalake kowé compute multiple conditional counts utawa sums ing siji query — technique kuwat kanggo reporting (effectively pivoting data).
ORDER BY CASE status
WHEN 'urgent' THEN 1
WHEN 'normal' THEN 2
ELSE 3
END; -- custom priority sort
CASE expression punika versatile, commonly-needed SQL feature kanggo nambaake conditional logic menyang queries — transforming, categorizing, lan conditionally computing values langsung ing SQL, dadi mangerti dheweke berharga kanggo real-world querying lan reporting.
Mangerti carane nggunaaken CASE ing SELECT (creating conditional/computed columns — kaya categorizing ages menyang groups, mapping codes menyang labels) punika frequent need kanggo shaping query output.
Particularly kuwat punika nggunaaken CASE sajroning aggregates (conditional counting lan summing — kaya counting active vs inactive ing siji query, utawa summing mung certain types) — key technique kanggo reporting lan analytics sing effectively pivots data, computing multiple conditional metrics ing siji efficient query. CASE ing ORDER BY ngemungkinake custom sort orders (priority-based sorting).
Mangerti loro-lorone searched form (evaluating conditions) lan simple form (matching a value), lan various contexts dene CASE applies, covers practical uses.
Menyang nambah conditional logic — categorizing data, conditional aggregation kanggo reports, custom sorting — punika common need ing querying lan especially ing reporting/analytics, lan menyang CASE punika standard, flexible way kanggo express logic iki langsung ing SQL (avoiding pulling data menyang application code kanggo simple transformations), mastering CASE expression punika useful, frequently-applied knowledge sing nambah expressive power menyang queries, particularly berharga kanggo conditional aggregation patterns central menyang SQL-based reporting lan data analysis.