准备可扩展类型系统工作，更合理的JOIN查询优化算法，并行查询

scripts/uninstall.ps1

@@ -0,0 +1,102 @@
+[CmdletBinding()]
+param(
+    [string]$InstallDir = '',
+    [string]$DataDir = '',
+    [switch]$KeepData,
+    [switch]$KeepConfig,
+    [switch]$Yes
+)
+
+$ErrorActionPreference = 'Stop'
+
+# Windows 卸载脚本：停服务、删程序与配置、从用户 PATH 摘掉安装目录。
+# 数据目录默认一起删，-KeepData 保留。
+
+# 打印步骤标题。
+function Step([string]$msg) { Write-Host ''; Write-Host "==> $msg" -ForegroundColor Cyan }
+# 打印一行输出。
+function Say([string]$msg) { Write-Host $msg }
+# 报错退出。
+function Fail([string]$msg) { Write-Host "!! $msg" -ForegroundColor Red; exit 1 }
+
+if (-not $InstallDir) { $InstallDir = Join-Path $env:LOCALAPPDATA 'ChuSQL' }
+if (-not $DataDir) { $DataDir = Join-Path $InstallDir 'data' }
+$InstallDir = [System.IO.Path]::GetFullPath($InstallDir)
+$DataDir = [System.IO.Path]::GetFullPath($DataDir)
+$configDir = if ($env:APPDATA) { Join-Path $env:APPDATA 'ChuSQL' } else { Join-Path $InstallDir 'config' }
+$configFile = Join-Path $configDir 'chusql.toml'
+
+if (-not $Yes) {
+    if ([Console]::IsInputRedirected) {
+        Fail 'no terminal: rerun with -Yes to confirm'
+    }
+    Say 'ChuSQL uninstaller'
+    Say ("  install dir  {0}" -f $InstallDir)
+    Say ("  data dir     {0}" -f $DataDir)
+    if ($KeepData) { Say '  data         kept' }
+    $answer = (Read-Host 'Remove it? [y/N]').Trim()
+    if ($answer -notmatch '^(y|yes)$') {
+        Say 'nothing was removed'
+        exit 0
+    }
+}
+
+Step 'Stopping the service'
+$running = @(Get-Process -Name 'chusql-server', 'chusql-web' -ErrorAction SilentlyContinue |
+    Where-Object {
+        try { $_.Path -and $_.Path.StartsWith($InstallDir, [StringComparison]::OrdinalIgnoreCase) }
+        catch { $false }
+    })
+foreach ($proc in $running) {
+    Stop-Process -Id $proc.Id -Force -ErrorAction SilentlyContinue
+    Say ("  stopped {0} (pid {1})" -f $proc.ProcessName, $proc.Id)
+}
+if ($running.Count -eq 0) { Say '  nothing was running' }
+
+Step 'Removing files'
+if (-not (Test-Path $InstallDir)) {
+    Say ("  not found: {0}" -f $InstallDir)
+} elseif ($KeepData) {
+    Get-ChildItem -LiteralPath $InstallDir -Force | ForEach-Object {
+        if ($_.FullName -eq $DataDir) {
+            Say ("  kept data: {0}" -f $_.FullName)
+        } else {
+            Remove-Item -LiteralPath $_.FullName -Recurse -Force -ErrorAction SilentlyContinue
+        }
+    }
+    Say ("  kept {0} (data only)" -f $InstallDir)
+} else {
+    Remove-Item -LiteralPath $InstallDir -Recurse -Force
+    if (-not $DataDir.StartsWith($InstallDir, [StringComparison]::OrdinalIgnoreCase)) {
+        Remove-Item -LiteralPath $DataDir -Recurse -Force -ErrorAction SilentlyContinue
+    }
+    Say ("  removed {0}" -f $InstallDir)
+}
+
+Step 'Removing chusql.toml'
+if ($KeepConfig) {
+    Say ("  kept config: {0}" -f $configFile)
+} else {
+    if (Test-Path $configFile) {
+        Remove-Item -LiteralPath $configFile -Force
+        Say ("  removed config: {0}" -f $configFile)
+    } else {
+        Say ("  no config file: {0}" -f $configFile)
+    }
+    if (Test-Path $configDir) { Remove-Item -LiteralPath $configDir -Force -ErrorAction SilentlyContinue }
+}
+
+Step 'Removing the PATH entry'
+$userPath = [Environment]::GetEnvironmentVariable('Path', 'User')
+if (-not $userPath) { $userPath = '' }
+$entries = @($userPath -split ';' | Where-Object { $_ })
+$updated = @($entries | Where-Object { $_ -ne $InstallDir })
+if ($updated.Count -ne $entries.Count) {
+    [Environment]::SetEnvironmentVariable('Path', ($updated -join ';'), 'User')
+    Say ("  removed {0} from the user PATH" -f $InstallDir)
+} else {
+    Say '  the user PATH has no install directory'
+}
+
+Step 'Done'
+Say '  open a new terminal: the old PATH stays in the current one'