Builder Pattern

interface QueryConfig {
  table: string;
  select: string[];
  where?: Record<string, unknown>;
  orderBy?: string;
  limit?: number;
}

class QueryBuilder {
  private config: Partial<QueryConfig> = {};

  from(table: string): this {
    this.config.table = table;
    return this;
  }

  select(...fields: string[]): this {
    this.config.select = fields;
    return this;
  }

  where(conditions: Record<string, unknown>): this {
    this.config.where = conditions;
    return this;
  }

  orderBy(field: string): this {
    this.config.orderBy = field;
    return this;
  }

  limit(count: number): this {
    this.config.limit = count;
    return this;
  }

  build(): QueryConfig {
    if (!this.config.table || !this.config.select) {
      throw new Error('table and select are required');
    }
    return this.config as QueryConfig;
  }
}

const query = new QueryBuilder()
  .from('users')
  .select('id', 'name', 'email')
  .where({ active: true })
  .orderBy('createdAt')
  .limit(10)
  .build();