Function abs 

pub fn abs<'a, V, E>(
    expr: E,
) -> SQLExpr<'a, V, E::SQLType, E::Nullable, E::Aggregate>
where
    V: SQLParam + 'a,
    E: Expr<'a, V>,
    E::SQLType: Numeric,

ABS - returns the absolute value of a number.

Preserves the SQL type and nullability of the input expression.

Type Safety

// ✅ OK: Int column
abs(users.balance);

// ❌ Compile error: Text is not Numeric
abs(users.name);