swift - 添加复杂查询后，项目的构建和运行时间过长

Question

我已经在我的一个 swift 项目中集成了 SQLite.swift 框架，一切都工作正常，直到我添加了以下查询。添加以下查询项目后，构建时间太长。我等了30分钟，但项目仍然没有得到满足。

do
{
let stmt = try DB!.prepare ("SELECT e." + ENDPOINT_ID + " as _id, lk." + HUB_ID + ", e." + X_ENDPOINT_ID + ", e." + ENDPOINT_DESC + ", e." + ENDPOINT_TYPE_ID +", et." + ENDPOINT_STATUS_MIN + ", et." + ENDPOINT_STATUS_MAX + ", e." + ENDPOINT_STATUS + " FROM " + TABLE_ENDPOINT + " as e INNER JOIN " + TABLE_ENDPOINT_TYPE + " as et " +
" ON e." + ENDPOINT_TYPE_ID + " = et." + ENDPOINT_TYPE_ID +
" INNER JOIN " + TABLE_LINKING + " as lk " +
" ON e." + ENDPOINT_ID + " = lk." + ENDPOINT_ID +
" INNER JOIN " + TABLE_NODE + " as n " +
" ON lk." + NODE_ID + " = n." + NODE_ID +
" INNER JOIN " + TABLE_NODE_TYPE + " as nt " +
" ON n." + NODE_TYPE_ID + " = nt." + NODE_TYPE_ID +
" WHERE lk." + SECTION_ID + "=" + section_Id +
" AND nt." + NODE_CATEGORY + " = "S" " +
" ORDER BY e." + ENDPOINT_ID + " ASC")

        let arr = Array(try stmt.run)

        print("\(arr)")
        return arr
    } catch {
        print("failed: \(error)")
        return []
    }

如果我注释上面的代码并尝试运行该项目，则运行该项目几乎不需要一分钟，但添加此代码后，需要花费大量时间。我已经等了将近 30 分钟，但该项目仍然没有编译，也没有抛出任何错误。预先感谢您的帮助

Answer 1

Swift 编译器在处理大字符串文字时遇到困难。另请参阅this question以获得进一步的提示。

我建议拆分 sql 并以小步骤构建字符串变量:

var sql = "SELECT e." + ENDPOINT_ID
sql = sql + HUB_ID + ", e."
sql = sql + X_ENDPOINT_ID + ", e."
...
let stmt = try DB!.prepare(sql)