SQL-457: How to return pivot table output?

table-operations/pivot-tables/dynamic-pivoting/inserting-data-into-table.sql

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+INSERT INTO Teaching (id, role, semester, year, course_id, faculty_id) 
+VALUES 
+(613, 'Instructor', 'SUMMER', 2023, 'CS111', 111), 
+(614, 'TA', 'SUMMER', 2023, 'CS111', 300), 
+(615, 'Instructor', 'SUMMER', 2023, 'CS112', 121), 
+(616, 'TA', 'SUMMER', 2023, 'CS112', 301); 
+
+INSERT INTO Teaching (id, role, semester, year, course_id, faculty_id) 
+VALUES 
+(617, 'Instructor', 'WINTER', 2023, 'CS113', 221), 
+(618, 'TA', 'WINTER', 2023, 'CS113', 302), 
+(619, 'Instructor', 'WINTER', 2023, 'CS121', 131);

table-operations/pivot-tables/dynamic-pivoting/mysql-dynamic-pivoting.sql

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+SET @sql = NULL; 
+SELECT GROUP_CONCAT(DISTINCT CONCAT( 
+    'COUNT(CASE WHEN semester = ''', semester, ''' THEN 1 END) AS `', semester, '`' ) ) 
+INTO @sql 
+FROM Teaching; 
+SET @sql = CONCAT('SELECT role, ', @sql, ' 
+                  FROM Teaching 
+                  GROUP BY role'); 
+PREPARE stmt FROM @sql; 
+EXECUTE stmt; 
+DEALLOCATE PREPARE stmt;

table-operations/pivot-tables/dynamic-pivoting/postgresql-dymanic-pivoting.sql

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+DO $$ 
+DECLARE 
+  cols TEXT; 
+  dyn_sql TEXT; 
+BEGIN 
+  SELECT string_agg( 
+      format('COALESCE(MAX(CASE WHEN semester = %L THEN count END), 0) AS "%s"', semester, semester), 
+      ', ' ) INTO cols 
+  FROM (SELECT DISTINCT semester FROM Teaching) s; 
+  dyn_sql := format(
+      $f$ 
+      SELECT role, %s 
+      FROM ( SELECT role, semester, COUNT(*) AS count FROM Teaching GROUP BY role, semester ) AS sub 
+      GROUP BY role 
+      ORDER BY role; 
+      $f$, cols); 
+      RAISE NOTICE 'Run this SQL: %', dyn_sql; 
+END $$;

table-operations/pivot-tables/dynamic-pivoting/sql-server-dynamic-pivoting.sql

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+DECLARE @columns NVARCHAR(MAX), @sql NVARCHAR(MAX); 
+SELECT @columns = STRING_AGG(QUOTENAME(semester), ', ') 
+FROM (SELECT DISTINCT semester FROM Teaching) AS semesters; 
+SET @sql = ' 
+  SELECT role, ' + @columns + ' 
+  FROM ( SELECT role, semester FROM Teaching ) AS source 
+  PIVOT ( COUNT(semester) FOR semester IN (' + @columns + ') ) AS pivot_table; 
+          '; 
+EXEC sp_executesql @sql;

table-operations/pivot-tables/pivoting-in-mysql.sql

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+SELECT 
+  role, 
+  COUNT(CASE WHEN semester = 'SPRING' THEN 1 END) AS spring_count, 
+  COUNT(CASE WHEN semester = 'FALL' THEN 1 END) AS fall_count 
+FROM teaching 
+GROUP BY role;

table-operations/pivot-tables/pivoting-in-postgresql.sql

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+-- Enabling the tablefunc extension so we can use crosstab()
+CREATE EXTENSION IF NOT EXISTS tablefunc;
+
+SELECT * 
+FROM crosstab( 
+  $$ 
+  SELECT role, semester, COUNT(*) 
+  FROM Teaching 
+  GROUP BY role, semester 
+  ORDER BY role, semester 
+  $$, 
+  $$ VALUES ('SPRING'), ('FALL') $$ 
+  ) AS ct(role TEXT, spring_count INT, fall_count INT);

table-operations/pivot-tables/pivoting-in-sql-server.sql

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+SELECT [role], 
+       [SPRING] AS spring_count, 
+       [FALL] as fall_count 
+FROM ( 
+  SELECT [role], semester 
+  FROM Teaching 
+  ) AS source 
+PIVOT ( 
+  COUNT(semester) 
+  FOR semester IN ([SPRING], [FALL]) 
+  ) AS pivot_table;