{"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=IQoJb3JpZ2luX2VjEFoaCWV1LXdlc3QtMSJHMEUCIAFYMf%2FpDBRN9Eg7bkEcYA473YaItJMlO%2FTAKuEJ1hBBAiEAw%2Bfs9%2FJ32Fml3T99X9Zj0nLtiQ9BYAa8D4QR7kXUUkQquQUIIxAFGgwyNzM1NzAxOTU0MzMiDAWzRcMJtZqlRYNikyqWBTUo3FOQTZ6n%2F05o54z%2B8oS0yWLxG2SWkuTwUyYtO0OlIBizMRevQwq4mUu0%2F%2FqVlxbUj09WAW3FPee6FDM9VxUb6eN%2B01O%2BtVEzBNUr8ElDCpLEtkxu2SgzGsg067ZOJ4icHUzNOQV251T7eM1Os2hO3jkr%2BjsC3I7zsEcgTPJSVv5xpZfQNFkYWo4kJV4ErHiXUqskN5xji6AhvXyH5P1IyZBmwxqDC1qNTbgTpiOEuS9YEznBt4%2FrEFDju%2FiZXXs2kWbMNVfHjFMi%2Bx2nk09VCZnHd%2BhVD4QSyqBUnSzr%2B6%2BDHbFHgyPl3LOObfmdodG%2BdQpZAewOdkPzaNi48beYdLhVCxZ62ebxWU4KWuxAQgonxnDgEMBp9z7IKTd9Bk18lXg5Dh%2Fg8aEusHg9hkgyZQTpisctJaanIVjOTuwC5JWrCGssUXk7m4%2BmEX9I5VqoUPmAUGgFPNBJ2zrZgwHCJmMVs%2BWGelb8idHZdhungXw5Md9J2ivtDrP%2FEGWPw56TF%2Fl68XUGel0eFT9MFgGET3UZL1wx1N2mnwnLvXPKnvQpyDW1fm57JG07J2tC3xqtF%2BvtHB4T1KTyfsafzCSNHeflBLF0KjNnAd6rmhrS2m6ecJj3mm6RGln8Lxz%2FrTXKzC8nXOnvpp6Do%2BC2Q4dRI9KgaPev7BsAkhiuBWIUHOEKBQmDXygc2LMN41qWWjKC5CJQ5uct%2Fdl5wWzdIZyvbwGhxm67mFWSNovmFywUEiFaA3b3Y00swPn%2FC%2BsycM%2BW223urj4Coeqhm78Fi%2BqBef%2BHNoMlZHewJi8Ya2YYogNAM4MIsfj5HLmXv%2B%2FjoFZnAzN75Bom4arC13tj3gZIpUk5xGdcLH1lwYWj5GdB27xqgQUiMK6twtAGOrEBlQFhODhRJaRrZCn15kD4tL0ifZ4KlLI5NQKfaZeMYPNWfZPl2YLaGCnyVLQNYUrX0vsQMZX9H7lzc%2FKFKJdhCXGO1jsbNyGIrtPm2bhIQAuzKJhYflcupOc5lZE3fdrfXsNuIihrI4FG5fVnkDLTrGFAkd1%2F9pnYYZomNoQPr%2BUs7N%2BdN7Dg0k4EvswaN7BDRAn2B0EdFNmD4A2c4zmpMotw7sIvcBDCClsrWyorJ3xJ&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UVH5SL4EY%2F20260522%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260522T174800Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=a6add71777d87b81baa425302155fae1a07473b1b243bbd9e693c01f0c755d0c 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=IQoJb3JpZ2luX2VjEFoaCWV1LXdlc3QtMSJHMEUCIAFYMf%2FpDBRN9Eg7bkEcYA473YaItJMlO%2FTAKuEJ1hBBAiEAw%2Bfs9%2FJ32Fml3T99X9Zj0nLtiQ9BYAa8D4QR7kXUUkQquQUIIxAFGgwyNzM1NzAxOTU0MzMiDAWzRcMJtZqlRYNikyqWBTUo3FOQTZ6n%2F05o54z%2B8oS0yWLxG2SWkuTwUyYtO0OlIBizMRevQwq4mUu0%2F%2FqVlxbUj09WAW3FPee6FDM9VxUb6eN%2B01O%2BtVEzBNUr8ElDCpLEtkxu2SgzGsg067ZOJ4icHUzNOQV251T7eM1Os2hO3jkr%2BjsC3I7zsEcgTPJSVv5xpZfQNFkYWo4kJV4ErHiXUqskN5xji6AhvXyH5P1IyZBmwxqDC1qNTbgTpiOEuS9YEznBt4%2FrEFDju%2FiZXXs2kWbMNVfHjFMi%2Bx2nk09VCZnHd%2BhVD4QSyqBUnSzr%2B6%2BDHbFHgyPl3LOObfmdodG%2BdQpZAewOdkPzaNi48beYdLhVCxZ62ebxWU4KWuxAQgonxnDgEMBp9z7IKTd9Bk18lXg5Dh%2Fg8aEusHg9hkgyZQTpisctJaanIVjOTuwC5JWrCGssUXk7m4%2BmEX9I5VqoUPmAUGgFPNBJ2zrZgwHCJmMVs%2BWGelb8idHZdhungXw5Md9J2ivtDrP%2FEGWPw56TF%2Fl68XUGel0eFT9MFgGET3UZL1wx1N2mnwnLvXPKnvQpyDW1fm57JG07J2tC3xqtF%2BvtHB4T1KTyfsafzCSNHeflBLF0KjNnAd6rmhrS2m6ecJj3mm6RGln8Lxz%2FrTXKzC8nXOnvpp6Do%2BC2Q4dRI9KgaPev7BsAkhiuBWIUHOEKBQmDXygc2LMN41qWWjKC5CJQ5uct%2Fdl5wWzdIZyvbwGhxm67mFWSNovmFywUEiFaA3b3Y00swPn%2FC%2BsycM%2BW223urj4Coeqhm78Fi%2BqBef%2BHNoMlZHewJi8Ya2YYogNAM4MIsfj5HLmXv%2B%2FjoFZnAzN75Bom4arC13tj3gZIpUk5xGdcLH1lwYWj5GdB27xqgQUiMK6twtAGOrEBlQFhODhRJaRrZCn15kD4tL0ifZ4KlLI5NQKfaZeMYPNWfZPl2YLaGCnyVLQNYUrX0vsQMZX9H7lzc%2FKFKJdhCXGO1jsbNyGIrtPm2bhIQAuzKJhYflcupOc5lZE3fdrfXsNuIihrI4FG5fVnkDLTrGFAkd1%2F9pnYYZomNoQPr%2BUs7N%2BdN7Dg0k4EvswaN7BDRAn2B0EdFNmD4A2c4zmpMotw7sIvcBDCClsrWyorJ3xJ&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UVH5SL4EY%2F20260522%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260522T174800Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=c19e2be8b726c9fe98678f40ee07cfb33422ee22f60ac741d6ef037c426340e5 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=IQoJb3JpZ2luX2VjEFoaCWV1LXdlc3QtMSJHMEUCIAFYMf%2FpDBRN9Eg7bkEcYA473YaItJMlO%2FTAKuEJ1hBBAiEAw%2Bfs9%2FJ32Fml3T99X9Zj0nLtiQ9BYAa8D4QR7kXUUkQquQUIIxAFGgwyNzM1NzAxOTU0MzMiDAWzRcMJtZqlRYNikyqWBTUo3FOQTZ6n%2F05o54z%2B8oS0yWLxG2SWkuTwUyYtO0OlIBizMRevQwq4mUu0%2F%2FqVlxbUj09WAW3FPee6FDM9VxUb6eN%2B01O%2BtVEzBNUr8ElDCpLEtkxu2SgzGsg067ZOJ4icHUzNOQV251T7eM1Os2hO3jkr%2BjsC3I7zsEcgTPJSVv5xpZfQNFkYWo4kJV4ErHiXUqskN5xji6AhvXyH5P1IyZBmwxqDC1qNTbgTpiOEuS9YEznBt4%2FrEFDju%2FiZXXs2kWbMNVfHjFMi%2Bx2nk09VCZnHd%2BhVD4QSyqBUnSzr%2B6%2BDHbFHgyPl3LOObfmdodG%2BdQpZAewOdkPzaNi48beYdLhVCxZ62ebxWU4KWuxAQgonxnDgEMBp9z7IKTd9Bk18lXg5Dh%2Fg8aEusHg9hkgyZQTpisctJaanIVjOTuwC5JWrCGssUXk7m4%2BmEX9I5VqoUPmAUGgFPNBJ2zrZgwHCJmMVs%2BWGelb8idHZdhungXw5Md9J2ivtDrP%2FEGWPw56TF%2Fl68XUGel0eFT9MFgGET3UZL1wx1N2mnwnLvXPKnvQpyDW1fm57JG07J2tC3xqtF%2BvtHB4T1KTyfsafzCSNHeflBLF0KjNnAd6rmhrS2m6ecJj3mm6RGln8Lxz%2FrTXKzC8nXOnvpp6Do%2BC2Q4dRI9KgaPev7BsAkhiuBWIUHOEKBQmDXygc2LMN41qWWjKC5CJQ5uct%2Fdl5wWzdIZyvbwGhxm67mFWSNovmFywUEiFaA3b3Y00swPn%2FC%2BsycM%2BW223urj4Coeqhm78Fi%2BqBef%2BHNoMlZHewJi8Ya2YYogNAM4MIsfj5HLmXv%2B%2FjoFZnAzN75Bom4arC13tj3gZIpUk5xGdcLH1lwYWj5GdB27xqgQUiMK6twtAGOrEBlQFhODhRJaRrZCn15kD4tL0ifZ4KlLI5NQKfaZeMYPNWfZPl2YLaGCnyVLQNYUrX0vsQMZX9H7lzc%2FKFKJdhCXGO1jsbNyGIrtPm2bhIQAuzKJhYflcupOc5lZE3fdrfXsNuIihrI4FG5fVnkDLTrGFAkd1%2F9pnYYZomNoQPr%2BUs7N%2BdN7Dg0k4EvswaN7BDRAn2B0EdFNmD4A2c4zmpMotw7sIvcBDCClsrWyorJ3xJ&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UVH5SL4EY%2F20260522%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260522T174800Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=414d0d64dda4059d486c333f52ba48ba5461419ea50922920d5982f0f852f8b6 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, https:\/\/glow-prod-sh.s3.eu-west-1.amazonaws.com\/sh\/public\/ahscomputingsql\/uploads\/sites\/3269\/2021\/03\/24125850\/DB4SQL-foreignkey-4-300x43.png?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&amp;X-Amz-Security-Token=IQoJb3JpZ2luX2VjEFoaCWV1LXdlc3QtMSJHMEUCIAFYMf%2FpDBRN9Eg7bkEcYA473YaItJMlO%2FTAKuEJ1hBBAiEAw%2Bfs9%2FJ32Fml3T99X9Zj0nLtiQ9BYAa8D4QR7kXUUkQquQUIIxAFGgwyNzM1NzAxOTU0MzMiDAWzRcMJtZqlRYNikyqWBTUo3FOQTZ6n%2F05o54z%2B8oS0yWLxG2SWkuTwUyYtO0OlIBizMRevQwq4mUu0%2F%2FqVlxbUj09WAW3FPee6FDM9VxUb6eN%2B01O%2BtVEzBNUr8ElDCpLEtkxu2SgzGsg067ZOJ4icHUzNOQV251T7eM1Os2hO3jkr%2BjsC3I7zsEcgTPJSVv5xpZfQNFkYWo4kJV4ErHiXUqskN5xji6AhvXyH5P1IyZBmwxqDC1qNTbgTpiOEuS9YEznBt4%2FrEFDju%2FiZXXs2kWbMNVfHjFMi%2Bx2nk09VCZnHd%2BhVD4QSyqBUnSzr%2B6%2BDHbFHgyPl3LOObfmdodG%2BdQpZAewOdkPzaNi48beYdLhVCxZ62ebxWU4KWuxAQgonxnDgEMBp9z7IKTd9Bk18lXg5Dh%2Fg8aEusHg9hkgyZQTpisctJaanIVjOTuwC5JWrCGssUXk7m4%2BmEX9I5VqoUPmAUGgFPNBJ2zrZgwHCJmMVs%2BWGelb8idHZdhungXw5Md9J2ivtDrP%2FEGWPw56TF%2Fl68XUGel0eFT9MFgGET3UZL1wx1N2mnwnLvXPKnvQpyDW1fm57JG07J2tC3xqtF%2BvtHB4T1KTyfsafzCSNHeflBLF0KjNnAd6rmhrS2m6ecJj3mm6RGln8Lxz%2FrTXKzC8nXOnvpp6Do%2BC2Q4dRI9KgaPev7BsAkhiuBWIUHOEKBQmDXygc2LMN41qWWjKC5CJQ5uct%2Fdl5wWzdIZyvbwGhxm67mFWSNovmFywUEiFaA3b3Y00swPn%2FC%2BsycM%2BW223urj4Coeqhm78Fi%2BqBef%2BHNoMlZHewJi8Ya2YYogNAM4MIsfj5HLmXv%2B%2FjoFZnAzN75Bom4arC13tj3gZIpUk5xGdcLH1lwYWj5GdB27xqgQUiMK6twtAGOrEBlQFhODhRJaRrZCn15kD4tL0ifZ4KlLI5NQKfaZeMYPNWfZPl2YLaGCnyVLQNYUrX0vsQMZX9H7lzc%2FKFKJdhCXGO1jsbNyGIrtPm2bhIQAuzKJhYflcupOc5lZE3fdrfXsNuIihrI4FG5fVnkDLTrGFAkd1%2F9pnYYZomNoQPr%2BUs7N%2BdN7Dg0k4EvswaN7BDRAn2B0EdFNmD4A2c4zmpMotw7sIvcBDCClsrWyorJ3xJ&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential=ASIAT7MQN47UVH5SL4EY%2F20260522%2Feu-west-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20260522T174800Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=900&amp;X-Amz-Signature=4f119a09cc096d80a77b339e28f5ff97bd208b3a167d686bcdf126cd3494814f 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}]}}