{"id":695,"date":"2026-10-23T12:55:45","date_gmt":"2026-10-23T02:55:45","guid":{"rendered":"https:\/\/www.desiderata.com.au\/blog\/?p=695"},"modified":"2026-10-23T12:55:45","modified_gmt":"2026-10-23T02:55:45","slug":"a-delphi-tclientdataset-gotcha-key-violation-error-when-using-master-detail-datasets","status":"publish","type":"post","link":"https:\/\/www.desiderata.com.au\/blog\/?p=695","title":{"rendered":"A Delphi TClientDataset gotcha – key violation error when using master-detail datasets"},"content":{"rendered":"\n

If you create a TClientDataset and make it a detail dataset of a master-detail link by setting its master properties, when you run your app and navigate through the Master dataset, the default settings will create a Key Violation error.<\/p>\n\n\n\n

This is easily remedied by setting your detail TClientDataset.packetRecords to -1.<\/p>\n\n\n\n

For some reason, every time you make a change to the master properties of this dataset, Delphi reverts the packetRecords back to zero which will cause the key violations.<\/p>\n","protected":false},"excerpt":{"rendered":"

If you create a TClientDataset and make it a detail dataset of a master-detail link by setting its master properties, when you run your app and navigate through the Master dataset, the default settings will create a Key Violation error. … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[9,47,48],"class_list":["post-695","post","type-post","status-publish","format-standard","hentry","category-delphi","tag-database-programming","tag-dephi","tag-tclientdatasets"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t