SQL DDL Data Definition Language

CREATE TABLE 〈table_name〉(
〈column_name〉 〈data_type〉,
〈column_name〉 〈data_type〉,
... PRIMARY KEY (〈column_name〉, 〈column_name〉, ...) );
SEE ALSO:
   CREATE TABLE 〈table name〉 AS 〈query〉;

#Example
%%sql
DROP TABLE IF EXISTS patient;
 CREATE TABLE patient (
   
    patient_id CHAR(4),
    patient_name VARCHAR(20),
    date_of_birth DATE,
    gender CHAR(6),
    height_cm DECIMAL(4,1),
    weight_kg DECIMAL(4,1),
    doctor_id CHAR(4),
   
    PRIMARY KEY (patient_id)
 );


DROP TABLE someTable;

DROP TABLE IF EXISTS someTable; 

ALTER TABLE ADD CONSTRAINT
ALTER TABLE 〈table name〉 ADD CONSTRAINT 〈constraint name〉 〈constraint definition〉; 

ALTER TABLE DROP CONSTRAINT
ALTER TABLE 〈table name〉 DROP CONSTRAINT 〈constraint name〉; 

ALTER TABLE ADD CONSTRAINT UNIQUE
ALTER TABLE 〈table name〉 
ADD CONSTRAINT 〈constraint name〉 
UNIQUE (〈column 1〉, 〈column 2〉, ..., 〈column n〉);  

ALTER TABLE ADD CONSTRAINT CHECK
ALTER TABLE 〈table name〉 ADD CONSTRAINT 〈constraint name〉 CHECK 〈condition〉; 

ALTER TABLE ADD CONSTRAINT primarykey
ALTER TABLE tableName ADD CONSTRAINT name_pk PRIMARY KEY (column); 

ALTER TABLE ADD CONSTRAINT foreignkey
 ALTER TABLE tableName ADD CONSTRAINT name_fk
 FOREIGN KEY (column) REFERENCES childTable;
Note: FK of tableName will reference PK of childTable