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';

Comments

Post a Comment

Popular posts from this blog

ios - How do I use CFArrayRef in Swift? -

I am using Objective-class in my Swift Project through a bridging header. The method signature looks like this: - Some cement (some type) some parameters; I started by getting an example of class, calling method, and storing the value: var myInstance = MyClassWithThatMethod (); Var cfArr = myInstance.someMethod (some value); Then try to get the value in the array: var valueInArrayThatIWant = CFArrayGetValueAtIndex (cfArr, 0); However, I get the error unmanaged & lt; Cfarray & gt; Not like 'CFArray' . Unmanaged & lt; Cfarray & gt; also means? I looked, but I do not need to change the array in a fast array (though it would be good). I need to be able to get value from the array. I also tried CFArray method to pass in a function: func doSomeStuffOnArray (myArray: NSArray) {} Although I get the same error when using: doSomeStuffOnArray (cfArr); // unmanaged & lt; CFArray & gt; I am using CFArray because I want to sto...
Read more

eclipse plugin - Run java code error: Workspace is closed -

To create an automated project, I created a plug-in project with the following dependencies: Org.eclipse.core.resources org.eclipse.equinox.registry org.eclipse.core.runtime and the following The Java class is located in the src folder: Package Examiner; Import org.eclipse.core.resources.IProject; Import org.eclipse.core.resources.IWorkspaceRoot; Import org.eclipse.core.resources.ResourcesPlugin; Import org.eclipse.core.runtime.CoreException; Import org.eclipse.core.runtime.IProgressMonitor; Import org.eclipse.core.runtime.NullProgressMonitor; Public class tes {public static zero main (string [] args) {// TODO auto generated method stub IProgressMonitor progress monitor = new NullProgressMonitor (); IWorkspaceRoot root = ResourcesPlugin.getWorkspace (). GetRoot (); Ipoject project = root.jetproject ("desired projectname"); Try {Project.create (progress monitor); Project.open (progressMonitor); } Grip (CoreException E) {// TODO Auto generated blocking block e....
Read more

c - Error on building source code in VC 6 -

When I create my project in VC6, the BScMKE reports the following error Linking .. Creating Library ... .. / ... / PB / Bean / Debub / ICEERP.Lib and Object ........ P.B. / Bean / DBube / ICREPlay.APP Browse information file ... BSMMK: ​​error can not be read from BK 1505: file '../../PB/bin/TmpOut/ICReplay/Debug/ICReplay_PB.bsc' Error executing bscmake.exe Can someone help me? 2 Reason for reference from: "ICReplay_PB .bsc "file will be corrupted The trunk of the file will be happening with the compiler running out of disk space or is being interrupted when creating .sbr file I think this answer will help you!
Read more