SQL

duplicate column values sql

-- copy values from old column to new column
UPDATE tablename SET new_column = old_column

duplicate table sql

CREATE TABLE new_table LIKE original_table;

sql how to duplicate a table

CREATE TABLE new_table LIKE original_table;
INSERT INTO new_table SELECT * FROM original_table;

duplicate records in sql

Multiple field=
SELECT username, email, COUNT(*)
FROM users
GROUP BY username, email
HAVING COUNT(*) > 1

Single field=
SELECT _column, COUNT(*) 
FROM _table
GROUP BY _column
HAVING COUNT(*) > 1

duplicate in sql

• SELECT first_name, COUNT (first_name) FROM employees
GROUP BY first_name
HAVING (COUNT(first_name) > 1);

sql duplicate a table with data

SELECT *
INTO NewTableName
FROM OriginalTable;

sql duplicate rows

/*SELECT hotel_id, reservation_id, COUNT(hotel_id)FROM staywhere  reservation_id is not nullGROUP BY hotel_id, reservation_idHAVING COUNT(hotel_id) > 1*/select distinct s.hotel_id , t.* from stay sright join (    select hotel_id, reservation_id, count(*) as qty    from staywhere reservation_id !=1      group by hotel_id, reservation_id    having count(*) > 1) t on s.hotel_id = t.hotel_id and s.reservation_id = t.reservation_id

duplicate a column in sql

ALTER TABLE Table1
ADD SubCategory2 {Type of subcategory 1} {NULL|NOT NULL} 
UPDATE Table1 SET SubCategory2 = SubCategory;