mac address - PostgreSQL 9.3: Migrate text column to macaddr type -

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मेरे पास एक एक मैक एड्रेस का प्रतिनिधित्व स्तंभ है , लेकिन मैं बजाय मैकड्र प्रकार टाइप करें इसलिए, मैंने कोशिश की: 

  तालिका mytable alter स्तंभ mac_column प्रकार macaddr;

और यह त्रुटि मिली 

  त्रुटि: कॉलम "मैककॉलूम" स्वचालित रूप से मैकड्र टाइप करने के लिए नहीं डाला जा सकता है HINT: कनवर्ज़न करने के लिए उपयोग की जाने वाली अभिव्यक्ति निर्दिष्ट करें

लेकिन मुझे पता नहीं है कि उपयोग की जाने वाली अभिव्यक्ति के रूप में क्या उपयोग करना है: 

  तालिका mytable में परिवर्तन स्तंभ mac_column प्रकार macaddr का उपयोग करते हुए (?????? ??)

उपयोग की अभिव्यक्ति के रूप में मुझे क्या करना चाहिए?

बहुत पहले से बहुत धन्यवाद

आप बस डेटा प्रकार को बदल नहीं सकते क्योंकि डेटा पहले से कॉलम में मौजूद है। चूंकि डेटा प्रकार स्ट्रिंग PostgreSQL है, क्योंकि यह मैकड्रंट के रूप में अपेक्षा नहीं कर सकता, हालांकि आपने macaddr के वैध स्ट्रिंग का प्रतिनिधित्व किया है। तो अब, जैसा कि पोस्टग्रेएसक्यूएल ने सुझाव दिया है कि आप अपने डेटा को macaddr में डालने के लिए 'यूजिंग' अभिव्यक्ति का उपयोग कर सकते हैं। 

  ALTER TABLE mytable ALTER COLUMN mac_column TYPE macaddr USING (mac_column: : मैकड्र)

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