使用 Powershell 从 PostgreSQL 检索数据

Question

我一直在努力解决从 Powershell 到 PostgreSQL 的数据库连接问题。我终于能够连接并插入到数据库中。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，我不包括我的插入内容，但稍后会将其添加到此线程上，因为我知道它很难找到并且可能对某人有帮助。

所以这是我的代码：

# 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

通过postgresql自带的psql

$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 C:\Program Files\PostgreSQL\12\bin。应该能够输入“psql”并在 powershell 中查看输出。

作为警告，请注意字符串。例如 $data[0].age.GetType() 将是字符串，尽管它作为整数存储在数据库中。您可以立即转换它，稍后转换它，或者希望 powershell 正确推断类型。

如果你想添加回类型信息可以这样做，例如：

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

Answer 2

我最终弄清楚了 - 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