Example 1: mysql change primary key
ALTER TABLE tableName MODIFY COLUMN id INT;
ALTER TABLE tableName DROP PRIMARY KEY;
ALTER TABLE tableName ADD PRIMARY KEY (new_id);
ALTER TABLE tableName MODIFY COLUMN new_id INT AUTO_INCREMENT;
Example 2: create table mysql query
create table tutorials_tbl(
tutorial_id INT NOT NULL AUTO_INCREMENT,
tutorial_title VARCHAR(100) NOT NULL,
tutorial_author VARCHAR(40) NOT NULL,
submission_date DATE,
PRIMARY KEY ( tutorial_id )
);
Example 3: sql primary key
SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner
FROM all_constraints cons, all_cons_columns cols
WHERE cols.table_name = 'CUSTOMERS'
AND cons.constraint_type = 'P'
AND cons.constraint_name = cols.constraint_name
AND cons.owner = cols.owner;
SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner
FROM all_constraints cons, all_cons_columns cols
WHERE cols.table_name = '<table-name>'
AND cons.constraint_type = 'P'
AND cons.constraint_name = cols.constraint_name
AND cons.owner = cols.owner;
Example 4: mysql create table
CREATE TABLE nom_de_la_table
(
colonne1 type_donnees,
colonne2 type_donnees,
colonne3 type_donnees,
colonne4 type_donnees
)
Example 5: MySQL Primary Key
Typically, you define the primary key for a table in the CREATE TABLE statement.
If the primary key has one column, you can use the PRIMARY KEY constraint as a column constraint:
CREATE TABLE table_name(
primary_key_column datatype PRIMARY KEY,
...
);
Example 6: identify primary key in sql table
SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner
FROM all_constraints cons, all_cons_columns cols
WHERE cols.table_name = '<table-name>'
AND cons.constraint_type = 'P'
AND cons.constraint_name = cols.constraint_name
AND cons.owner = cols.owner
SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner
FROM all_constraints cons, all_cons_columns cols
WHERE cols.table_name = 'CUSTOMERS'
AND cons.constraint_type = 'P'
AND cons.constraint_name = cols.constraint_name
AND cons.owner = cols.owner