{"id":195,"date":"2021-03-22T14:54:38","date_gmt":"2021-03-22T14:54:38","guid":{"rendered":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/?page_id=195"},"modified":"2021-03-25T15:36:53","modified_gmt":"2021-03-25T15:36:53","slug":"primary-key","status":"publish","type":"page","link":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/creating-a-database\/primary-key\/","title":{"rendered":"Primary &amp; Foreign Keys"},"content":{"rendered":"<h1><span style=\"color: #339966\">Level &#8211; National 5+<\/span><\/h1>\n<h1>Primary Key<\/h1>\n<p>Every table should have a primary key &#8211; a unique identifier for each record.<\/p>\n<p>Primary keys are required (Not Null), and\u00a0must be unique<\/p>\n<ul>\n<li>Right-click on the Table name<\/li>\n<li>Select &#8220;Modify table&#8221;<\/li>\n<li>Tick the NN, PK and U options for the primary key<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-301\" src=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24122947\/DB4SQL-primary-key.png\" alt=\"\" width=\"610\" height=\"82\" srcset=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24122947\/DB4SQL-primary-key.png 610w, https:\/\/glow-prod-sh.s3.eu-west-1.amazonaws.com\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24122947\/DB4SQL-primary-key-300x40.png?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&amp;X-Amz-Security-Token=IQoJb3JpZ2luX2VjEJL%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaCWV1LXdlc3QtMSJHMEUCIQCgw6Td%2Bvl0K7llVOjiPyOgV3Fr7Q0IwxYTseHeGRNHggIgWyzLSa3qgATE8F%2FJCpjadY6sQqy3Mi90XlGYjjcmdLgquQUIWxAFGgwyNzM1NzAxOTU0MzMiDN7pHe%2BjBMOefiQLbCqWBbNVS7nTG2kBU%2Bh4tRtQASrODP9DZhLJ9cyFMHm0B0ryFkI6AomM71KhDfJHU%2Bwed36mkRelQutEcj5pLSQqMI6%2FenFy4AKS0wd6slVnAGybthqpcNe8ey8%2FQELdxZz1RlWP%2BkeKBxqOOxQnj2ivgd71r%2F%2F06z7rdXrIslJN3Pg0ZCh5PPRsa1LDjcXrj%2Buc103XUwduBxPogpfvqxzp3Yjl%2FNGC9aPMg%2FphI24x2CyAQr1JXL10XzO2VtBNCpXYpIMdfDW7yf3B0hBdAb35HrFVIgTm0ALoJ5%2FTx%2Bh6GjGTtiI4rgDgbyS%2FP%2BuvvGCSPw14Et4X9ufM%2FQ6KJhVjp1euBXATfZayms38d1Ma8GANA6nuVMf4%2BqxJsSl0oNurIcf3qlK0987HG9c9%2FW5T%2BrCCo02U7f1B01%2FnmPyMesfT2f9oJAQ%2BHSiDbSavKwXrMipI%2B%2F3cfjDlC405W%2FgDHhMht8lYdBdLvselQsw3ehSvsonxps%2FFCR12GjrkpaMYTmqBR4DLqTfvH1i%2BleR04rW0R0H5jHAQ3%2BKhNLFR9FM2koYbxipBK%2By0mY7HPervEDWPzL3PdVnRFvAcEN74weocYVurobL%2Bk%2Bdei4ztEYAMaAgwLYN5wnN0gLkS2l8%2Fc0MMmHZolVhJs%2F8HQmCR9XeIBq%2FPEXaviR4bhV7aN8uLN5Sc6SLnsj7fAAgiGCdr39nsIZMnpjjjKUEUsBWhPHW%2FftPDbils5651nDXH%2BLO8IwmUobW2E1Afqaf9wRIP6i%2B0eOWmMtrmjWA4XPtpzWKhv6JPISkCstg28vSfptXc4HVYdSMCaKQMhMbcH7rM8WoyjkQhC4W%2BZthZoc%2FXxoC61gFYAiOcfWkkJI24Ak8BIbcVKwSfMOTMr9IGOrEBqoS3sekn1uJnA5FOSBCmAid%2BRFYW6L1oqavwQQLsaBh%2FnJXFby5fWd%2FaRbxCiQfqvNtSTGNF96UTjTtPHq0VLcOr0kzEfLJWJJLO4oCbljc0oUPICMs3pgR%2BAkrb7QSTVdtj9sbqkPbaqu9lEEpfXfi4IXR5QPFPDEbWZb0rvau3UnwqPa29Xw1h6TVXWyvQh2afgUgKGpa0fimlC5gAUqsx5JQnhj8huVBAJC5V5FJW&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UX6EZ3NBF%2F20260706%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260706T182441Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=4ce7c1c2fa2920b8af09dcb14548d64e92d153501647c73e3f03ed9372b9c006 300w\" sizes=\"auto, (max-width: 610px) 100vw, 610px\" \/><\/li>\n<\/ul>\n<hr \/>\n<h1>Foreign Key<\/h1>\n<p>A foreign key connects each record in a table to a record in another table. The other table must be created before the tables can be linked.<br \/>\n<em>eg Each record in &#8220;appointments&#8221; table will link to a customer. The customers table must be created before the appointments table.<\/em><\/p>\n<ul>\n<li>Right-click on the Table that has the foreign key<\/li>\n<li>Select &#8220;Modify table&#8221;<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-308\" src=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125204\/DB4SQL-foreignkey-1.png\" alt=\"\" width=\"334\" height=\"160\" srcset=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125204\/DB4SQL-foreignkey-1.png 334w, 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300w\" sizes=\"auto, (max-width: 334px) 100vw, 334px\" \/><\/li>\n<li>Widen the table so you can see the Foreign Key column<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-307\" src=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125203\/DB4SQL-foreignkey-2.png\" alt=\"\" width=\"497\" height=\"160\" srcset=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125203\/DB4SQL-foreignkey-2.png 497w, https:\/\/glow-prod-sh.s3.eu-west-1.amazonaws.com\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125203\/DB4SQL-foreignkey-2-300x97.png?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&amp;X-Amz-Security-Token=IQoJb3JpZ2luX2VjEJL%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaCWV1LXdlc3QtMSJHMEUCIQCgw6Td%2Bvl0K7llVOjiPyOgV3Fr7Q0IwxYTseHeGRNHggIgWyzLSa3qgATE8F%2FJCpjadY6sQqy3Mi90XlGYjjcmdLgquQUIWxAFGgwyNzM1NzAxOTU0MzMiDN7pHe%2BjBMOefiQLbCqWBbNVS7nTG2kBU%2Bh4tRtQASrODP9DZhLJ9cyFMHm0B0ryFkI6AomM71KhDfJHU%2Bwed36mkRelQutEcj5pLSQqMI6%2FenFy4AKS0wd6slVnAGybthqpcNe8ey8%2FQELdxZz1RlWP%2BkeKBxqOOxQnj2ivgd71r%2F%2F06z7rdXrIslJN3Pg0ZCh5PPRsa1LDjcXrj%2Buc103XUwduBxPogpfvqxzp3Yjl%2FNGC9aPMg%2FphI24x2CyAQr1JXL10XzO2VtBNCpXYpIMdfDW7yf3B0hBdAb35HrFVIgTm0ALoJ5%2FTx%2Bh6GjGTtiI4rgDgbyS%2FP%2BuvvGCSPw14Et4X9ufM%2FQ6KJhVjp1euBXATfZayms38d1Ma8GANA6nuVMf4%2BqxJsSl0oNurIcf3qlK0987HG9c9%2FW5T%2BrCCo02U7f1B01%2FnmPyMesfT2f9oJAQ%2BHSiDbSavKwXrMipI%2B%2F3cfjDlC405W%2FgDHhMht8lYdBdLvselQsw3ehSvsonxps%2FFCR12GjrkpaMYTmqBR4DLqTfvH1i%2BleR04rW0R0H5jHAQ3%2BKhNLFR9FM2koYbxipBK%2By0mY7HPervEDWPzL3PdVnRFvAcEN74weocYVurobL%2Bk%2Bdei4ztEYAMaAgwLYN5wnN0gLkS2l8%2Fc0MMmHZolVhJs%2F8HQmCR9XeIBq%2FPEXaviR4bhV7aN8uLN5Sc6SLnsj7fAAgiGCdr39nsIZMnpjjjKUEUsBWhPHW%2FftPDbils5651nDXH%2BLO8IwmUobW2E1Afqaf9wRIP6i%2B0eOWmMtrmjWA4XPtpzWKhv6JPISkCstg28vSfptXc4HVYdSMCaKQMhMbcH7rM8WoyjkQhC4W%2BZthZoc%2FXxoC61gFYAiOcfWkkJI24Ak8BIbcVKwSfMOTMr9IGOrEBqoS3sekn1uJnA5FOSBCmAid%2BRFYW6L1oqavwQQLsaBh%2FnJXFby5fWd%2FaRbxCiQfqvNtSTGNF96UTjTtPHq0VLcOr0kzEfLJWJJLO4oCbljc0oUPICMs3pgR%2BAkrb7QSTVdtj9sbqkPbaqu9lEEpfXfi4IXR5QPFPDEbWZb0rvau3UnwqPa29Xw1h6TVXWyvQh2afgUgKGpa0fimlC5gAUqsx5JQnhj8huVBAJC5V5FJW&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UX6EZ3NBF%2F20260706%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260706T182441Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=678c7a8befdfb5c8d4899df6d5d5a11fee72cfd7158077021919aea7deeaff02 300w\" sizes=\"auto, (max-width: 497px) 100vw, 497px\" \/><\/li>\n<\/ul>\n<ul>\n<li>Double-click where the foreign key row and the Foreign Key column cross:<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-309\" src=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125636\/DB4SQL-foreignkey-3.png\" alt=\"\" width=\"606\" height=\"83\" srcset=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125636\/DB4SQL-foreignkey-3.png 606w, https:\/\/glow-prod-sh.s3.eu-west-1.amazonaws.com\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125636\/DB4SQL-foreignkey-3-300x41.png?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&amp;X-Amz-Security-Token=IQoJb3JpZ2luX2VjEJL%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaCWV1LXdlc3QtMSJHMEUCIQCgw6Td%2Bvl0K7llVOjiPyOgV3Fr7Q0IwxYTseHeGRNHggIgWyzLSa3qgATE8F%2FJCpjadY6sQqy3Mi90XlGYjjcmdLgquQUIWxAFGgwyNzM1NzAxOTU0MzMiDN7pHe%2BjBMOefiQLbCqWBbNVS7nTG2kBU%2Bh4tRtQASrODP9DZhLJ9cyFMHm0B0ryFkI6AomM71KhDfJHU%2Bwed36mkRelQutEcj5pLSQqMI6%2FenFy4AKS0wd6slVnAGybthqpcNe8ey8%2FQELdxZz1RlWP%2BkeKBxqOOxQnj2ivgd71r%2F%2F06z7rdXrIslJN3Pg0ZCh5PPRsa1LDjcXrj%2Buc103XUwduBxPogpfvqxzp3Yjl%2FNGC9aPMg%2FphI24x2CyAQr1JXL10XzO2VtBNCpXYpIMdfDW7yf3B0hBdAb35HrFVIgTm0ALoJ5%2FTx%2Bh6GjGTtiI4rgDgbyS%2FP%2BuvvGCSPw14Et4X9ufM%2FQ6KJhVjp1euBXATfZayms38d1Ma8GANA6nuVMf4%2BqxJsSl0oNurIcf3qlK0987HG9c9%2FW5T%2BrCCo02U7f1B01%2FnmPyMesfT2f9oJAQ%2BHSiDbSavKwXrMipI%2B%2F3cfjDlC405W%2FgDHhMht8lYdBdLvselQsw3ehSvsonxps%2FFCR12GjrkpaMYTmqBR4DLqTfvH1i%2BleR04rW0R0H5jHAQ3%2BKhNLFR9FM2koYbxipBK%2By0mY7HPervEDWPzL3PdVnRFvAcEN74weocYVurobL%2Bk%2Bdei4ztEYAMaAgwLYN5wnN0gLkS2l8%2Fc0MMmHZolVhJs%2F8HQmCR9XeIBq%2FPEXaviR4bhV7aN8uLN5Sc6SLnsj7fAAgiGCdr39nsIZMnpjjjKUEUsBWhPHW%2FftPDbils5651nDXH%2BLO8IwmUobW2E1Afqaf9wRIP6i%2B0eOWmMtrmjWA4XPtpzWKhv6JPISkCstg28vSfptXc4HVYdSMCaKQMhMbcH7rM8WoyjkQhC4W%2BZthZoc%2FXxoC61gFYAiOcfWkkJI24Ak8BIbcVKwSfMOTMr9IGOrEBqoS3sekn1uJnA5FOSBCmAid%2BRFYW6L1oqavwQQLsaBh%2FnJXFby5fWd%2FaRbxCiQfqvNtSTGNF96UTjTtPHq0VLcOr0kzEfLJWJJLO4oCbljc0oUPICMs3pgR%2BAkrb7QSTVdtj9sbqkPbaqu9lEEpfXfi4IXR5QPFPDEbWZb0rvau3UnwqPa29Xw1h6TVXWyvQh2afgUgKGpa0fimlC5gAUqsx5JQnhj8huVBAJC5V5FJW&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UX6EZ3NBF%2F20260706%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260706T182441Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=70da51f5b50be2e688318922b61df332adfd03a0de275ce72ee7a46e5e22779a 300w\" sizes=\"auto, (max-width: 606px) 100vw, 606px\" \/><\/li>\n<li>Use the drop-down menus to select the other table, and its primary key:<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-310\" src=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125850\/DB4SQL-foreignkey-4.png\" alt=\"\" width=\"607\" height=\"87\" srcset=\"https:\/\/blogs.glowscotland.org.uk\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125850\/DB4SQL-foreignkey-4.png 607w, 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300w\" sizes=\"auto, (max-width: 607px) 100vw, 607px\" \/><\/li>\n<li>Click inside the grey &#8220;Foreign key clauses&#8230;&#8221; box, and press the Enter key<\/li>\n<li>Check the code in the bottom panel, and press the OK button<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Level &#8211; National 5+ Primary Key Every table should have a primary key &#8211; a unique identifier for each record. Primary keys are required (Not Null), and\u00a0must be unique Right-click on the Table name Select &#8220;Modify table&#8221; Tick the NN, PK and U options for the primary key Foreign Key A foreign key connects each record in a table to a record in another table. The other table must be<\/p>\n<p><a class=\"more-link\" href=\"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/creating-a-database\/primary-key\/\">Read More<\/a><\/p>\n","protected":false},"author":7,"featured_media":0,"parent":262,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-195","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/pages\/195","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/comments?post=195"}],"version-history":[{"count":10,"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/pages\/195\/revisions"}],"predecessor-version":[{"id":407,"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/pages\/195\/revisions\/407"}],"up":[{"embeddable":true,"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/pages\/262"}],"wp:attachment":[{"href":"https:\/\/blogs.glowscotland.org.uk\/sh\/ahscomputingsql\/wp-json\/wp\/v2\/media?parent=195"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}