使用 Powershell 从 PostgreSQL 检索数据

Question

我一直在努力解决从 Powershell 到 PostgreSQL 的数据库连接。我终于能够连接并插入数据库。现在我不知道如何从数据库选择中提取数据到变量中。

为了清楚起见，我没有包括我的插入内容，但稍后会将其添加到此线程中，因为我知道它非常难以找到并且可能对某人有所帮助。

这是我的代码：

# use existing 64 bit ODBC System DSN that we set up manually
$DBconn = New-Object -comobject ADODB.Connection
$DBconn.Open("PostgreSQL35W")

$theQuery = "select * from test1"
$theObject = $DBconn.Execute($theQuery) # $theObject is a System.__ComObject
$numRecords = $theObject.RecordCount
write-host "found $numRecords records"  # getting -1
$theObject.MoveFirst()  # throws no error
# $theValue = $theObject.DataMember # throws no error, but gives no result
$theValue = $theObject.Index[1] # throws "Cannot index into a null array" 
write-host($theValue)

Answer 1

我对@dog 有一个稍微不同的方法，我无法让 --csv 工作，所以我只使用元组返回的行，然后将它们解析为一个类列表（恰好称为 OnlineCourses） ：

class OnlineCourse
{
    [int]$id
    [string]$email
    [string]$courseName
    [int]$completedRatio
    [datetime]$lastActivity
    [String]$provider
    OnlineCourse([int]$id,
        [string]$email,
        [string]$courseName,
        [int]$completedPerc,
        [datetime]$lastActivity,
        [String]$provider) {
            $this.id = $id
            $this.email = $email.Trim()
            $this.courseName = $courseName.Trim()
            $this.completedRatio = $completedPerc
            $this.lastActivity = $lastActivity
            $this.provider = $provider.Trim()
    }
}

$connstr="postgresql://exusername:expw@exhostname:5432/postgres"
$data = "select * from onlinecourses" | .\psql -t $connstr

$list = New-Object Collections.Generic.List[OnlineCourse]

foreach ($field in $data) { 
    $id, $email, $courseName,  $completedratio, $lastactivity, $provider = $field.split('|')
    $course = [OnlineCourse]::new($id, $email, $courseName, $completedratio, $lastactivity, $provider)
    $list.Add($course)
}

Answer 2

使用点符号。您不需要拆分数据。

$list = New-Object Collections.Generic.List[OnlineCourse]

foreach($element in $results)
{
    $tempObj= New-Object OnlineCourse($element.id,$element.courseName,$element.completedRatio,$element.completedRatio,$element.lastActivity, $element.provider)
    $list.add($tempObj)
}

Answer 3

通过 psql，postgresql 自带

$dburl="postgresql://exusername:expw@exhostname:5432/postgres"
$data="select * from extable" | psql --csv $dburl | ConvertFrom-Csv

您的路径中必须有 psql 或引用它，例如它在C:\Program Files\PostgreSQL\12\bin。应该能够键入“psql”并在 powershell 中查看输出。

作为警告，请期待字符串。例如 $data[0].age.GetType() 将是字符串，尽管它以整数形式存储在数据库中。您可以立即转换它，稍后再转换它，或者希望 powershell 正确推断类型。

如果你想添加回类型信息可以做例如：

$data = $data | %{[pscustomobject]@{name=$_.name;age=[int]$_.age}}

Answer 4

试试这个
将“#database#”替换为 $cnString
中的数据库名称 将“#server_ip#”替换为 $cnString 中的服务器 IP 地址
将“#user#”替换为 $cnString 和 $user
中的有效用户 将“#pass#”替换为 $pass
中的有效通行证 用您的数据库的有效表名替换“#table#”
用您的数据库端口替换 5432

$cnString = "DRIVER={PostgreSQL Unicode(x64)};DATABASE=#database#;SERVER=#server_ip#;PORT=5432;UID=#user#;"
$user="#user#"
$pass="#pass#"

$conn = New-Object -comobject ADODB.Connection
$conn.Open($cnString,$user,$pass)

$recordset = $conn.Execute("SELECT * FROM #table# limit 1;")
while ($recordset.EOF -ne $True) 
{  
    foreach ($field in $recordset.Fields)
    {    
        '{0,30} = {1,-30}' -f # this line sets up a nice pretty field format, but you don't really need it
        $field.name, $field.value  
    }
   ''  # this line adds a line between records
$recordset.MoveNext()
}

$conn.Close();

Answer 5

我最终弄明白了——这就是我所做的

$conn = New-Object -comobject ADODB.Connection

# use existing 64 bit ODBC System DSN that we set up manually
$conn.Open("PostgreSQL35W")

$recordset = $conn.Execute("SELECT * FROM JobHistory")
while ($recordset.EOF -ne $True) 
{  
    foreach ($field in $recordset.Fields)
    {    
        '{0,30} = {1,-30}' -f # this line sets up a nice pretty field format, but you don't really need it
        $field.name, $field.value  
    }
   ''  # this line adds a line between records
$recordset.MoveNext()
}

$conn.Close();
Exit