public static <T> Expression<T> set(Path<T> target, T value) {
        if (value != null) {
            return Expressions.operation(target.getType(), SQLOps.SET_LITERAL,
                    target, Expressions.constant(value));
        } else {
            return Expressions.operation(target.getType(), SQLOps.SET_LITERAL,
                    target, Expressions.nullExpression());
        }

    }
Create an assignment expression

@param target target expression
@param value value to be set
@param <T>
@return target = value
querydsl-sql/src/main/java/com/querydsl/sql/SQLExpressions.java