Merge branch 'Baeldung:main' into main

daKeshra · web-flow · commit 2739a08c895c · 2024-09-17T10:42:22.000-07:00
diff --git a/sql-queries-4/insert-from-select/insert-from-select.sql b/sql-queries-4/insert-from-select/insert-from-select.sql
@@ -0,0 +1,4 @@
+INSERT INTO registration_analytics(student_id, number_of_course_enrolled, year) 
+SELECT student_id, COUNT(course_id) AS number_of_course_enrolled, year 
+FROM registration 
+GROUP BY course_id, student_id, year;
diff --git a/sql-queries-5/README b/sql-queries-5/README
@@ -0,0 +1 @@
+
diff --git a/sql-queries-5/delete-column-from-table/delete-column-from-table.sql b/sql-queries-5/delete-column-from-table/delete-column-from-table.sql
diff --git a/sql-queries-5/delete-column-from-table/delete-columns-from-table-mssql.sql b/sql-queries-5/delete-column-from-table/delete-columns-from-table-mssql.sql
diff --git a/sql-queries-5/delete-column-from-table/delete-columns-from-table-mysql.sql b/sql-queries-5/delete-column-from-table/delete-columns-from-table-mysql.sql
diff --git a/sql-queries-5/delete-column-from-table/delete-columns-from-table-pg.sql b/sql-queries-5/delete-column-from-table/delete-columns-from-table-pg.sql
diff --git a/sql-queries-5/diff-setautocommit=1-starttransaction-mysql/autocommit-enabled.sql b/sql-queries-5/diff-setautocommit=1-starttransaction-mysql/autocommit-enabled.sql
@@ -0,0 +1,13 @@
+SET autocommit=1; --Turns on automatic transaction mode
+
+CREATE TABLE Department
+(
+    id INT PRIMARY KEY NOT Null,
+    name VARCHAR (50),
+    code VARCHAR (4),
+    UNIQUE (id)
+); -- Runs in a separate transaction
+
+SELECT SELECT * FROM DEPARTMENT; --Runs in a separate transaction
+
+INSERT INTO Department VALUES(6,'Data Science','DS'); --Runs in a separate transaction
diff --git a/sql-queries-5/diff-setautocommit=1-starttransaction-mysql/set-autocommit.sql b/sql-queries-5/diff-setautocommit=1-starttransaction-mysql/set-autocommit.sql
@@ -0,0 +1,15 @@
+SET autocommit=1; --Enables autocommit mode
+
+/*These are equivalent*/
+SET autocommit = DEFAULT;
+
+SET autocommit='ON';
+SET @@autocommit = 'ON';
+
+SET SESSION autocommit = 'ON';
+SET @@SESSION.autocommit = 'ON';
+
+SET LOCAL autocommit = 'ON';
+SET @@LOCAL.autocommit = 'ON';
+
+SELECT @@autocommit; --Query autocommit mode
diff --git a/sql-queries-5/diff-setautocommit=1-starttransaction-mysql/start-transaction.sql b/sql-queries-5/diff-setautocommit=1-starttransaction-mysql/start-transaction.sql
@@ -0,0 +1,9 @@
+START TRANSACTION; --Starts a single transaction
+
+/* SQL Statements*/
+SELECT SELECT * FROM DEPARTMENT;
+INSERT INTO Department VALUES(6,'Data Science','DS');
+INSERT INTO Department VALUES(7,'Computer Engineering','CE');
+UPDATE Department SET name = 'Math' WHERE id=5;  
+
+COMMIT; -- or ROLLBACK ends the single transaction
diff --git a/sql-queries-5/insert-if-not-exists/insert-if-not-exists-mysql.sql b/sql-queries-5/insert-if-not-exists/insert-if-not-exists-mysql.sql
@@ -0,0 +1,9 @@
+-- Using INSERT IGNORE
+INSERT IGNORE INTO table_name (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+VALUES (id_value, name_value, national_id_value, birth_date_value, enrollment_date_value, graduation_date_value, gpa_value);
+
+
+-- Using INSERT … ON DUPLICATE KEY UPDATE
+INSERT INTO table_name (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+VALUES (id_value, name_value, national_id_value, birth_date_value, enrollment_date_value, graduation_date_value, gpa_value)
+ON DUPLICATE KEY UPDATE id = id;
diff --git a/sql-queries-5/insert-if-not-exists/insert-if-not-exists-postgresql.sql b/sql-queries-5/insert-if-not-exists/insert-if-not-exists-postgresql.sql
@@ -0,0 +1,17 @@
+-- Using INSERT … ON CONFLICT
+INSERT INTO table_name (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+VALUES (id_value, name_value, national_id_value, birth_date_value, enrollment_date_value, graduation_date_value, gpa_value)
+ON CONFLICT (id) DO NOTHING;
+
+-- Using a DO Block
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM table_name WHERE id = id_value
+    ) THEN
+        INSERT INTO table_name (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+        VALUES (id_value, name_value, national_id_value, birth_date_value, enrollment_date_value, graduation_date_value, gpa_value);
+    ELSE
+        RAISE NOTICE 'A student already exists with this id. No insertion performed!';
+    END IF;
+END $$;
diff --git a/sql-queries-5/insert-if-not-exists/insert-if-not-exists-sqlserver.sql b/sql-queries-5/insert-if-not-exists/insert-if-not-exists-sqlserver.sql
@@ -0,0 +1,16 @@
+-- Using MERGE
+MERGE INTO table_name AS target
+USING (VALUES (id_value, name_value, national_id_value, birth_date_value, enrollment_date_value, graduation_date_value, gpa_value))
+       AS source (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+ON target.id = source.id
+WHEN NOT MATCHED BY TARGET THEN
+    INSERT (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+    VALUES (source.id, source.name, source.national_id, source.birth_date, source.enrollment_date, source.graduation_date, source.gpa);
+
+-- Using EXCEPT
+INSERT INTO table_name (id, name, national_id, birth_date, enrollment_date, graduation_date, gpa)
+SELECT id_value, name_value, national_id_value, birth_date_value, enrollment_date_value, graduation_date_value, gpa_value
+EXCEPT
+SELECT id, name, national_id, birth_date, enrollment_date, graduation_date, gpa
+FROM table_name
+WHERE id = id_value;
diff --git a/sql-queries-5/remove-primarykey-mysql/add-duplicate-id.sql b/sql-queries-5/remove-primarykey-mysql/add-duplicate-id.sql
@@ -0,0 +1,2 @@
+INSERT INTO Department_Duplicate(id,name,code) 
+VALUES(1,'Data Science','DS');
diff --git a/sql-queries-5/remove-primarykey-mysql/add-null-value.sql b/sql-queries-5/remove-primarykey-mysql/add-null-value.sql
@@ -0,0 +1,2 @@
+INSERT INTO Department_Duplicate(id,name,code) 
+VALUES(NULL,'Data Science','DS');
diff --git a/sql-queries-5/remove-primarykey-mysql/add-second-pk-failed.sql b/sql-queries-5/remove-primarykey-mysql/add-second-pk-failed.sql
@@ -0,0 +1,2 @@
+ALTER TABLE REGISTRATION 
+ADD PRIMARY KEY (course_id);
diff --git a/sql-queries-5/remove-primarykey-mysql/alter-table-add-pk.sql b/sql-queries-5/remove-primarykey-mysql/alter-table-add-pk.sql
@@ -0,0 +1,2 @@
+ALTER TABLE REGISTRATION 
+ADD PRIMARY KEY (id);
diff --git a/sql-queries-5/remove-primarykey-mysql/alter-table-column-nullable.sql b/sql-queries-5/remove-primarykey-mysql/alter-table-column-nullable.sql
@@ -0,0 +1,5 @@
+ALTER TABLE Department_Duplicate 
+MODIFY id INT NULL;
+
+ALTER TABLE REGISTRATION 
+MODIFY id INT NULL;
diff --git a/sql-queries-5/remove-primarykey-mysql/alter-table-drop-pk.sql b/sql-queries-5/remove-primarykey-mysql/alter-table-drop-pk.sql
@@ -0,0 +1,5 @@
+ALTER TABLE Department_Duplicate 
+DROP PRIMARY KEY;
+
+ALTER TABLE REGISTRATION 
+DROP PRIMARY KEY;
diff --git a/sql-queries-5/remove-primarykey-mysql/create-department-duplicate.sql b/sql-queries-5/remove-primarykey-mysql/create-department-duplicate.sql
@@ -0,0 +1,8 @@
+CREATE TABLE Department_Duplicate(
+    id INT PRIMARY KEY,
+    name VARCHAR (50),
+    code VARCHAR (4)
+ );
+
+INSERT INTO Department_Duplicate(id,name,code) 
+VALUES(1,'Data Science','DS');
diff --git a/sql-queries-5/remove-primarykey-mysql/describe-table.sql b/sql-queries-5/remove-primarykey-mysql/describe-table.sql
@@ -0,0 +1,3 @@
+DESC REGISTRATION;
+
+DESC Department_Duplicate;
diff --git a/sql-queries-5/remove-primarykey-mysql/drop-pk-in-transaction.sql b/sql-queries-5/remove-primarykey-mysql/drop-pk-in-transaction.sql
@@ -0,0 +1,6 @@
+START TRANSACTION;
+
+ALTER TABLE REGISTRATION 
+DROP PRIMARY KEY;
+
+ROLLBACK;
diff --git a/sql-queries-5/remove-primarykey-mysql/list-table-constraints.sql b/sql-queries-5/remove-primarykey-mysql/list-table-constraints.sql
@@ -0,0 +1,3 @@
+SELECT constraint_name, constraint_type
+FROM information_schema.table_constraints
+WHERE table_name = 'registration';
diff --git a/sql-queries-5/remove-primarykey-mysql/set-var.sql b/sql-queries-5/remove-primarykey-mysql/set-var.sql
@@ -0,0 +1,4 @@
+SET SESSION sql_require_primary_key = 'ON'
+
+ALTER TABLE REGISTRATION 
+DROP PRIMARY KEY;
diff --git a/sql-queries-5/remove-primarykey-mysql/show-var-sql_require_primary_key.sql b/sql-queries-5/remove-primarykey-mysql/show-var-sql_require_primary_key.sql
@@ -0,0 +1,3 @@
+SHOW VARIABLES LIKE 'sql_require_primary_key';
+
+SHOW SESSION VARIABLES LIKE 'sql_require_primary_key';
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/altering-student-table-MySQL-PostgreSQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/altering-student-table-MySQL-PostgreSQL.sql
@@ -0,0 +1,9 @@
+ALTER TABLE Student ADD COLUMN formatted_id VARCHAR(10);
+
+UPDATE Student 
+SET formatted_id = CONCAT('0', id) 
+WHERE id <= 2000;
+
+UPDATE Student 
+SET formatted_id = id 
+WHERE formatted_id IS NULL;
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/altering-student-table-SQL-Server.sql b/sql-queries-5/removing-leading-zeros-in-sql/altering-student-table-SQL-Server.sql
@@ -0,0 +1,12 @@
+-- Add a new column to the Student table 
+ALTER TABLE Student ADD formatted_id VARCHAR(10); 
+
+-- Update the new column with leading zeros 
+UPDATE Student 
+SET formatted_id = '0' + CAST(id AS VARCHAR(10))
+WHERE id <= 2000;
+
+-- Update remaining rows where formatted_id is NULL 
+UPDATE Student 
+SET formatted_id = CAST(id AS VARCHAR(10)) 
+WHERE formatted_id IS NULL;
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/example-formatted-data.sql b/sql-queries-5/removing-leading-zeros-in-sql/example-formatted-data.sql
@@ -0,0 +1,3 @@
+SELECT name, formatted_id 
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/trimming-with-MySQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/trimming-with-MySQL.sql
@@ -0,0 +1,4 @@
+SELECT name, formatted_id,
+       TRIM(LEADING '0' FROM formatted_id) AS cleaned_id
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/trimming-with-PostgreSQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/trimming-with-PostgreSQL.sql
@@ -0,0 +1,4 @@
+SELECT name, formatted_id,
+       LTRIM(formatted_id, '0') AS cleaned_id
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/trimming-with-SQL-Server.sql b/sql-queries-5/removing-leading-zeros-in-sql/trimming-with-SQL-Server.sql
@@ -0,0 +1,7 @@
+SELECT name, formatted_id,
+       SUBSTRING(formatted_id, 
+                 PATINDEX('%[^0]%', formatted_id), 
+                 LEN(formatted_id)
+       ) AS cleaned_id
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/using-CAST-function-MySQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/using-CAST-function-MySQL.sql
@@ -0,0 +1,4 @@
+SELECT name, formatted_id,
+       CAST(formatted_id AS UNSIGNED) AS cleaned_id
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/using-CAST-function-PostgreSQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/using-CAST-function-PostgreSQL.sql
@@ -0,0 +1,6 @@
+SELECT 
+	name, 
+    formatted_id, 
+    CAST(formatted_id AS INTEGER) AS cleaned_id 
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/using-CAST-function-SQL-Server.sql b/sql-queries-5/removing-leading-zeros-in-sql/using-CAST-function-SQL-Server.sql
@@ -0,0 +1,6 @@
+SELECT 
+	name, 
+    formatted_id, 
+    CAST(formatted_id AS INT) AS cleaned_id 
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/using-CONVERT-function-with-MySQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/using-CONVERT-function-with-MySQL.sql
@@ -0,0 +1,6 @@
+SELECT 
+	name, 
+	formatted_id, 
+    CONVERT(formatted_id, UNSIGNED) AS cleaned_id 
+FROM Student 
+WHERE id IN (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/using-CONVERT-function-with-PosgreSQL.sql b/sql-queries-5/removing-leading-zeros-in-sql/using-CONVERT-function-with-PosgreSQL.sql
@@ -0,0 +1,6 @@
+SELECT 
+	name, 
+    formatted_id, 
+    formatted_id::INTEGER AS cleaned_id 
+FROM Student 
+WHERE id IN (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/removing-leading-zeros-in-sql/using-CONVERT-function-with-SQL-Server.sql b/sql-queries-5/removing-leading-zeros-in-sql/using-CONVERT-function-with-SQL-Server.sql
@@ -0,0 +1,6 @@
+SELECT 
+	name, 
+    formatted_id, 
+    CONVERT(INT, formatted_id) AS cleaned_id 
+FROM Student 
+WHERE id in (1607,1007,2017,1010,1111,2008);
diff --git a/sql-queries-5/select-butoom-N-row-in-sql/using-orderby-and-limit-postgresql.sql b/sql-queries-5/select-butoom-N-row-in-sql/using-orderby-and-limit-postgresql.sql
@@ -0,0 +1,4 @@
+SELECT id, name, gpa
+FROM Student
+ORDER BY gpa ASC
+LIMIT 5;
diff --git a/sql-queries-5/select-butoom-N-row-in-sql/using-orderby-and-offset-fetch-clause-sqlserver.sql b/sql-queries-5/select-butoom-N-row-in-sql/using-orderby-and-offset-fetch-clause-sqlserver.sql
@@ -0,0 +1,6 @@
+SELECT id, name, gpa
+FROM Student
+WHERE gpa IS NOT NULL
+ORDER BY gpa ASC
+OFFSET (SELECT COUNT(*) FROM Student WHERE gpa IS NOT NULL) - 5 ROWS
+FETCH NEXT 5 ROWS ONLY;
diff --git a/sql-queries-5/select-butoom-N-row-in-sql/using-rownumber-window-function-postgresql.sql b/sql-queries-5/select-butoom-N-row-in-sql/using-rownumber-window-function-postgresql.sql
@@ -0,0 +1,8 @@
+WITH RankedStudents AS (
+    SELECT id, name, gpa,
+           ROW_NUMBER() OVER (ORDER BY gpa ASC) AS row_num
+    FROM Student
+)
+SELECT id, name, gpa
+FROM RankedStudents
+WHERE row_num <= 5;
diff --git a/sql-queries-5/select-butoom-N-row-in-sql/using-rownumber-window-function-sqlserver.sql b/sql-queries-5/select-butoom-N-row-in-sql/using-rownumber-window-function-sqlserver.sql
@@ -0,0 +1,10 @@
+WITH RankedStudents AS (
+    SELECT id, name, gpa,
+           ROW_NUMBER() OVER (ORDER BY gpa ASC) AS row_num
+    FROM Student
+    WHERE gpa IS NOT NULL
+)
+SELECT id, name, gpa
+FROM RankedStudents
+WHERE row_num <= 5
+ORDER BY gpa ASC;
diff --git a/sql-queries-5/select-butoom-N-row-in-sql/using-subqueries-with-orderby-mysql.sql b/sql-queries-5/select-butoom-N-row-in-sql/using-subqueries-with-orderby-mysql.sql
@@ -0,0 +1,8 @@
+SELECT id, name, gpa
+FROM (
+    SELECT id, name, gpa
+    FROM Student
+    ORDER BY gpa ASC
+    LIMIT 5
+) AS BottomStudents
+ORDER BY gpa ASC;
diff --git a/sql-queries-5/split-column-values-into-multiple-columns/split-column-values-into-multiple-columns-mysql.sql b/sql-queries-5/split-column-values-into-multiple-columns/split-column-values-into-multiple-columns-mysql.sql
@@ -0,0 +1,29 @@
+-- Using SUBSTRING_INDEX Function
+
+SELECT 
+    SUBSTRING_INDEX(column_name, ' ', 1) AS new_column_name_1, 
+    SUBSTRING_INDEX(column_name, ' ', -1) AS new_column_name_2 
+FROM 
+    table_name;
+   
+-- Handling More Complex Scenarios
+   
+SELECT 
+    SUBSTRING_INDEX(column_name, ' ', 1) AS new_column_name_1, 
+    SUBSTRING(column_name, LOCATE(' ', column_name) + 1, LOCATE(' ', column_name, LOCATE(' ', column_name) + 1) - LOCATE(' ', column_name) - 1) AS new_column_name_2, 
+    SUBSTRING_INDEX(column_name, ' ', -1) AS new_column_name_3
+FROM 
+    table_name;
+   
+-- Handling Extra Spaces and Multiple Delimiters
+
+SELECT 
+    SUBSTRING_INDEX(TRIM(REPLACE(column_name, '  ', ' ')), ' ', 1) AS new_column_name_1, 
+    SUBSTRING_INDEX(TRIM(REPLACE(column_name, '  ', ' ')), ' ', -1) AS new_column_name_2 
+FROM table_name;
+
+
+SELECT 
+    SUBSTRING_INDEX(REPLACE(REPLACE(column_name, '-', ' '), '_', ' '), ' ', 1) AS new_column_name_1, 
+    SUBSTRING_INDEX(REPLACE(REPLACE(column_name, '-', ' '), '_', ' '), ' ', -1) AS new_column_name_2 
+FROM table_name;
diff --git a/sql-queries-5/split-column-values-into-multiple-columns/split-column-values-into-multiple-columns-postgresql.sql b/sql-queries-5/split-column-values-into-multiple-columns/split-column-values-into-multiple-columns-postgresql.sql
@@ -0,0 +1,33 @@
+-- Using SPLIT_PART Function
+
+SELECT 
+    SPLIT_PART(column_name, ' ', 1) AS new_column_name_1, 
+    SPLIT_PART(column_name, ' ', 2) AS new_column_name_2
+FROM table_name;
+
+-- Using STRING_TO_ARRAY Function
+
+WITH name_array AS (
+    SELECT 
+        STRING_TO_ARRAY(column_name, ' ') AS name_parts
+    FROM table_name 
+)
+SELECT 
+    name_parts[1] AS new_column_name_1, 
+    name_parts[2] AS new_column_name_2 
+FROM name_array;
+
+-- Handling More Complex Scenarios
+
+WITH name_array AS (
+   SELECT 
+       STRING_TO_ARRAY(column_name, ' ') AS name_parts
+   FROM table_name 
+) 
+SELECT 
+    name_parts[1] AS new_column_name_1,
+    CASE WHEN array_length(name_parts, 1) = 3 THEN name_parts[2] END AS new_column_name_2,
+    CASE WHEN array_length(name_parts, 1) = 3 THEN name_parts[3] 
+         WHEN array_length(name_parts, 1) = 2 THEN name_parts[2] 
+    END AS new_column_name_3 
+FROM name_array;
diff --git a/sql-queries-5/sql-over-clause/over-clause-with-group-by.sql b/sql-queries-5/sql-over-clause/over-clause-with-group-by.sql
@@ -0,0 +1,5 @@
+SELECT enrollment_date,
+MAX(gpa) AS highest_gpa,
+MIN(gpa) AS lowest_gpa
+FROM Student
+GROUP BY enrollment_date;
diff --git a/sql-queries-5/sql-over-clause/over-clause-with-order-by.sql b/sql-queries-5/sql-over-clause/over-clause-with-order-by.sql
@@ -0,0 +1,5 @@
+SELECT id, semester, grade,
+MAX(grade) OVER (PARTITION BY student_id ORDER BY grade) AS course_highest,
+MIN(grade) OVER (PARTITION BY student_id ORDER BY grade) AS course_lowest
+FROM Exam
+ORDER BY course_id;
diff --git a/sql-queries-5/sql-over-clause/over-clause-with-partition-by.sql b/sql-queries-5/sql-over-clause/over-clause-with-partition-by.sql
@@ -0,0 +1,3 @@
+SELECT name, position,
+COUNT(*) OVER (PARTITION BY name) AS Total_Positions
+FROM Faculty;
diff --git a/sql-queries-5/sql-over-clause/over-clause-with-rows.sql b/sql-queries-5/sql-over-clause/over-clause-with-rows.sql
@@ -0,0 +1,5 @@
+SELECT id, enrollment_date,
+AVG(gpa) OVER (ORDER BY enrollment_date ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS Avg3GPAs,
+AVG(gpa) OVER (ORDER BY YEAR(enrollment_date) RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS AvgGPAYearOverYear
+FROM Student
+ORDER BY enrollment_date, id;
diff --git a/sql-queries-dates/group-year-month/grouping-mssql.sql b/sql-queries-dates/group-year-month/grouping-mssql.sql
diff --git a/sql-queries-dates/group-year-month/grouping-mysql.sql b/sql-queries-dates/group-year-month/grouping-mysql.sql
diff --git a/sql-queries-dates/group-year-month/grouping-pg.sql b/sql-queries-dates/group-year-month/grouping-pg.sql
