{"id":3928,"date":"2025-06-06T20:38:00","date_gmt":"2025-06-06T20:38:00","guid":{"rendered":"https:\/\/w3buddy.com\/?post_type=cposts&#038;p=3928"},"modified":"2025-06-07T09:57:15","modified_gmt":"2025-06-07T09:57:15","slug":"sql-update","status":"publish","type":"cposts","link":"https:\/\/w3buddy.com\/blog\/notes\/sql\/sql-update\/","title":{"rendered":"SQL UPDATE"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">The <code>UPDATE<\/code> statement is used to <strong>change data<\/strong> in existing rows of a table.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udd39 Basic Syntax<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code><code>UPDATE table_name\nSET column1 = value1, column2 = value2, ...\nWHERE condition;<\/code><\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u26a0\ufe0f <strong>Always use a WHERE clause<\/strong> unless you want to update <em>every row<\/em>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udd39 Example<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code><code>-- Increase salary of employee with ID 101\nUPDATE employees\nSET salary = salary + 5000\nWHERE employee_id = 101;\n\n-- Update department for multiple employees\nUPDATE employees\nSET department = 'Finance'\nWHERE department = 'Accounts';<\/code><\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udd39 Update All Rows (Be Careful!)<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code><code>-- Set a default value for all rows\nUPDATE employees\nSET bonus = 0;<\/code><\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udd39 With Subqueries (Advanced)<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code><code>-- Set manager name from another table\nUPDATE employees e\nSET manager_name = (\n  SELECT name FROM managers m WHERE m.id = e.manager_id\n)\nWHERE EXISTS (\n  SELECT 1 FROM managers m WHERE m.id = e.manager_id\n);<\/code><\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83e\udde0 Quick Recap<\/h2>\n\n\n\n<figure class=\"wp-block-table has-small-font-size\"><table><thead><tr><th>Use Case<\/th><th>Example Syntax<\/th><\/tr><\/thead><tbody><tr><td>Update specific row<\/td><td><code>UPDATE table SET col = val WHERE ...<\/code><\/td><\/tr><tr><td>Update multiple rows<\/td><td>Use conditions in <code>WHERE<\/code> clause<\/td><\/tr><tr><td>No WHERE = all rows<\/td><td>Updates all rows (\u26a0\ufe0f risky!)<\/td><\/tr><tr><td>Use expressions<\/td><td><code>SET col = col + 1000<\/code><\/td><\/tr><tr><td>Use subqueries<\/td><td><code>SET col = (SELECT ...)<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u2705 Use <code>UPDATE<\/code> to modify your data precisely<br><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The UPDATE statement is used to change data in existing rows of a table. \ud83d\udd39 Basic Syntax \u26a0\ufe0f Always use a WHERE clause unless you want to update every row. \ud83d\udd39 Example \ud83d\udd39 Update All Rows (Be Careful!) \ud83d\udd39 With Subqueries (Advanced) \ud83e\udde0 Quick Recap Use Case Example Syntax Update specific row UPDATE table SET [&hellip;]<\/p>\n","protected":false},"template":"","meta":{"googlesitekit_rrm_CAowu461DA:productID":""},"categories":[952,979],"class_list":["post-3928","cposts","type-cposts","status-publish","hentry","category-notes","category-sql"],"_links":{"self":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/cposts\/3928","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/cposts"}],"about":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/types\/cposts"}],"wp:attachment":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/media?parent=3928"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/categories?post=3928"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}