Class JoinCondition

Namespace: YndigoBlue.Velocity.Model

Assembly: YndigoBlue.Velocity.dll

Represents the ON condition in a SQL JOIN clause that specifies which columns to join on.

public class JoinCondition

Inheritance: object

JoinCondition

Examples

Simple equality join (most common):

// JOIN users ON orders.user_id = users.id
JoinCondition joinCondition = new JoinCondition(
    ordersTable["user_id"],
    usersTable["id"]
);

Join join = new Join(ordersTable, usersTable, joinCondition, JoinType.Inner);

Query query = new Query();
query.AddFromItem(join);
query.AddSelectItem(ordersTable["order_date"]);
query.AddSelectItem(usersTable["username"]);

// SQL: SELECT orders.order_date, users.username
//      FROM orders
//      INNER JOIN users ON orders.user_id = users.id

Explicit equality join:

// Same as above but with explicit operator
JoinCondition joinCondition = new JoinCondition(
    ordersTable["user_id"],
    JoinOperatorType.Equals,
    usersTable["id"]
);

Join join = new Join(ordersTable, usersTable, joinCondition, JoinType.Inner);

Non-equality join:

// Find orders with prices higher than the product's base price
// JOIN products ON orders.price > products.base_price
JoinCondition joinCondition = new JoinCondition(
    ordersTable["price"],
    JoinOperatorType.GreaterThan,
    productsTable["base_price"]
);

Join join = new Join(ordersTable, productsTable, joinCondition, JoinType.Inner);

// SQL: FROM orders
//      INNER JOIN products ON orders.price > products.base_price

Multiple joins with different conditions:

// First join: orders with users
JoinCondition userJoin = new JoinCondition(
    ordersTable["user_id"],
    usersTable["id"]
);

Join firstJoin = new Join(ordersTable, usersTable, userJoin, JoinType.Inner);

// Second join: add addresses
JoinCondition addressJoin = new JoinCondition(
    usersTable["address_id"],
    addressesTable["id"]
);

Join secondJoin = new Join(firstJoin, addressesTable, addressJoin, JoinType.Left);

Query query = new Query();
query.AddFromItem(secondJoin);

// SQL: FROM orders
//      INNER JOIN users ON orders.user_id = users.id
//      LEFT JOIN addresses ON users.address_id = addresses.id

Remarks

JoinCondition defines the relationship between two tables in a JOIN operation. It specifies which columns from each table should be compared and what comparison operator to use.

While equality (=) is by far the most common join operator, Velocity also supports other comparison operators like >, <, >=, <=, and <> for advanced join scenarios.

Constructors

JoinCondition(ISelectItem, JoinOperatorType, ISelectItem): Creates a new join condition with a specified comparison operator.

JoinCondition(ISelectItem, ISelectItem): Creates a new join condition using equality comparison (most common).

Fields

_firstSelectItem

_joinOperatorType

_secondSelectItem

Properties

FirstSelectItem: Gets the column from the left table in the join comparison.

JoinOperatorType: Gets the comparison operator used in the join condition (=, >, <, etc.).