Add Column If Not Exists in Postgresql -


इस सवाल का पहले से ही एक उत्तर है: < 9 उत्तर

है postgresql ( 9.3.2 ) एक नया स्तंभ जोड़ने से पहले एक स्तंभ के अस्तित्व को जांच सकते हैं? मैं अस्तित्व की जांच करने के लिए सिर्फ एक फ़ंक्शन नहीं बनाना चाहता हूं।

बस इस तरह से: 

  वैकल्पिक तालिका में मौजूद नहीं है तो तालिका का नाम कॉलम कॉलम_नाम डेटा_प्रकार;

आपको अपने स्वयं की संग्रहीत कार्यविधि को plpgsql में लिखना होगा ताकि यह जांच सके कि तालिका क्या है इस कॉलम में है इसके लिए आपको तालिकाओं PG_ATTRIBUTE और PG_CLASS की आवश्यकता होगी जहां Postgres स्कीमा मेटाडेटा को संग्रहीत करता है और विशेष रूप से कॉलम और तालिकाओं के बारे में जानकारी क्रमशः।

क्वेरी जिसका परिणाम आपको अपनी संग्रहीत कार्यविधि में जांचना होगा जैसे शामिल हों: 

  SELECT A.ATTNAME से PG_ATTRIBUTE A, PG_CLASS C जहां एटट्र्रेडिट = सीओआईडी और एएटीटीएन = 'column_name_check_if_exists' और crelname = 'table_name';

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