{"id":2613,"date":"2025-03-11T23:30:46","date_gmt":"2025-03-11T15:30:46","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=2613"},"modified":"2025-03-11T23:30:46","modified_gmt":"2025-03-11T15:30:46","slug":"postgresql-%e8%bf%90%e7%ae%97%e7%ac%a6%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/03\/11\/postgresql-%e8%bf%90%e7%ae%97%e7%ac%a6%e8%af%a6%e8%a7%a3\/","title":{"rendered":"PostgreSQL \u8fd0\u7b97\u7b26\u8be6\u89e3"},"content":{"rendered":"\n

\u5728 PostgreSQL \u4e2d\uff0c\u8fd0\u7b97\u7b26\u7528\u4e8e\u6267\u884c\u5404\u79cd\u64cd\u4f5c\uff0c\u5982\u6570\u5b66\u8ba1\u7b97\u3001\u6bd4\u8f83\u3001\u903b\u8f91\u5224\u65ad\u3001\u5b57\u7b26\u4e32\u64cd\u4f5c\u7b49\u3002PostgreSQL \u652f\u6301\u591a\u79cd\u8fd0\u7b97\u7b26\uff0c\u5305\u62ec\u7b97\u672f\u8fd0\u7b97\u7b26\u3001\u6bd4\u8f83\u8fd0\u7b97\u7b26\u3001\u903b\u8f91\u8fd0\u7b97\u7b26\u3001\u4f4d\u8fd0\u7b97\u7b26\u3001\u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26\u7b49\u3002<\/p>\n\n\n\n

\n\n\n\n

1. \u7b97\u672f\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n

\u7b97\u672f\u8fd0\u7b97\u7b26\u7528\u4e8e\u6267\u884c\u57fa\u672c\u7684\u6570\u5b66\u8ba1\u7b97\u3002<\/p>\n\n\n\n

\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th>\u7ed3\u679c<\/th><\/tr><\/thead>
+<\/code><\/td>\u52a0\u6cd5<\/td>SELECT 10 + 5;<\/code><\/td>15<\/td><\/tr>
-<\/code><\/td>\u51cf\u6cd5<\/td>SELECT 10 - 5;<\/code><\/td>5<\/td><\/tr>
*<\/code><\/td>\u4e58\u6cd5<\/td>SELECT 10 * 5;<\/code><\/td>50<\/td><\/tr>
\/<\/code><\/td>\u9664\u6cd5<\/td>SELECT 10 \/ 5;<\/code><\/td>2<\/td><\/tr>
%<\/code><\/td>\u53d6\u6a21<\/td>SELECT 10 % 3;<\/code><\/td>1<\/td><\/tr>
^<\/code><\/td>\u5e42\u8fd0\u7b97<\/td>SELECT 2 ^ 3;<\/code><\/td>8<\/td><\/tr>
|\/<\/code><\/td>\u5e73\u65b9\u6839<\/td>SELECT |\/ 9;<\/code><\/td>3<\/td><\/tr>
||\/<\/code><\/td>\u7acb\u65b9\u6839<\/td>SELECT ||\/ 27;<\/code><\/td>3<\/td><\/tr>
!<\/code><\/td>\u9636\u4e58<\/td>SELECT 5!;<\/code><\/td>120<\/td><\/tr>
@<\/code><\/td>\u7edd\u5bf9\u503c<\/td>SELECT @ -10;<\/code><\/td>10<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

\u793a\u4f8b\uff1a<\/p>\n\n\n\n

SELECT 15 % 4;  -- \u7ed3\u679c\uff1a3\nSELECT 3 ^ 3;   -- \u7ed3\u679c\uff1a27<\/code><\/pre>\n\n\n\n
\n\n\n\n
2. \u6bd4\u8f83\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
\u6bd4\u8f83\u8fd0\u7b97\u7b26\u7528\u4e8e\u6bd4\u8f83\u4e24\u4e2a\u503c\uff0c\u5e76\u8fd4\u56de TRUE<\/code> \u6216 FALSE<\/code>\u3002<\/p>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th>\u7ed3\u679c<\/th><\/tr><\/thead>
=<\/code><\/td>\u7b49\u4e8e<\/td>SELECT 10 = 10;<\/code><\/td>TRUE<\/td><\/tr>
<><\/code> \u6216 !=<\/code><\/td>\u4e0d\u7b49\u4e8e<\/td>SELECT 10 <> 5;<\/code><\/td>TRUE<\/td><\/tr>
<<\/code><\/td>\u5c0f\u4e8e<\/td>SELECT 10 < 5;<\/code><\/td>FALSE<\/td><\/tr>
><\/code><\/td>\u5927\u4e8e<\/td>SELECT 10 > 5;<\/code><\/td>TRUE<\/td><\/tr>
<=<\/code><\/td>\u5c0f\u4e8e\u7b49\u4e8e<\/td>SELECT 10 <= 10;<\/code><\/td>TRUE<\/td><\/tr>
>=<\/code><\/td>\u5927\u4e8e\u7b49\u4e8e<\/td>SELECT 10 >= 11;<\/code><\/td>FALSE<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT * FROM employees WHERE salary > 5000;<\/code><\/pre>\n\n\n\n
\n\n\n\n
3. \u903b\u8f91\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
\u903b\u8f91\u8fd0\u7b97\u7b26\u7528\u4e8e\u7ec4\u5408\u591a\u4e2a\u6761\u4ef6\u3002<\/p>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th><\/tr><\/thead>
AND<\/code><\/td>\u903b\u8f91\u4e0e<\/td>SELECT * FROM employees WHERE age > 30 AND salary > 6000;<\/code><\/td><\/tr>
OR<\/code><\/td>\u903b\u8f91\u6216<\/td>SELECT * FROM employees WHERE age < 25 OR salary > 7000;<\/code><\/td><\/tr>
NOT<\/code><\/td>\u903b\u8f91\u975e<\/td>SELECT * FROM employees WHERE NOT (department = 'IT');<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT * FROM employees WHERE age > 30 AND salary > 6000;<\/code><\/pre>\n\n\n\n
\n\n\n\n
4. \u4f4d\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
\u4f4d\u8fd0\u7b97\u7b26\u7528\u4e8e\u6309\u4f4d\u64cd\u4f5c\u3002<\/p>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th>\u7ed3\u679c<\/th><\/tr><\/thead>
&<\/code><\/td>\u6309\u4f4d\u4e0e<\/td>SELECT 5 & 3;<\/code><\/td>1<\/td><\/tr>
|<\/code><\/td>\u6309\u4f4d\u6216<\/td>SELECT 5 | 3;<\/code><\/td>7<\/td><\/tr>
#<\/code><\/td>\u6309\u4f4d\u5f02\u6216<\/td>SELECT 5 # 3;<\/code><\/td>6<\/td><\/tr>
~<\/code><\/td>\u6309\u4f4d\u53d6\u53cd<\/td>SELECT ~5;<\/code><\/td>-6<\/td><\/tr>
<<<\/code><\/td>\u5de6\u79fb<\/td>SELECT 5 << 1;<\/code><\/td>10<\/td><\/tr>
>><\/code><\/td>\u53f3\u79fb<\/td>SELECT 5 >> 1;<\/code><\/td>2<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT 10 & 6;  -- \u7ed3\u679c\uff1a2\nSELECT 10 | 6;  -- \u7ed3\u679c\uff1a14\nSELECT 5 << 2;  -- \u7ed3\u679c\uff1a20<\/code><\/pre>\n\n\n\n
\n\n\n\n
5. \u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
\u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26\u7528\u4e8e\u5904\u7406\u5b57\u7b26\u4e32\u3002<\/p>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th>\u7ed3\u679c<\/th><\/tr><\/thead>
||<\/code><\/td>\u8fde\u63a5\u5b57\u7b26\u4e32<\/td>SELECT 'Hello' || ' World';<\/code><\/td>Hello World<\/code><\/td><\/tr>
LIKE<\/code><\/td>\u6a21\u5f0f\u5339\u914d<\/td>SELECT * FROM employees WHERE name LIKE 'A%';<\/code><\/td>\u5339\u914d\u4ee5 A \u5f00\u5934\u7684\u540d\u5b57<\/td><\/tr>
ILIKE<\/code><\/td>\u5927\u5c0f\u5199\u4e0d\u654f\u611f\u5339\u914d<\/td>SELECT * FROM employees WHERE name ILIKE 'a%';<\/code><\/td>Alice<\/code> \u548c alice<\/code> \u90fd\u80fd\u5339\u914d<\/td><\/tr>
SIMILAR TO<\/code><\/td>\u6b63\u5219\u5339\u914d<\/td>SELECT 'abcd' SIMILAR TO 'a_%d';<\/code><\/td>TRUE<\/td><\/tr>
~<\/code><\/td>\u6b63\u5219\u8868\u8fbe\u5f0f\u5339\u914d<\/td>SELECT 'hello' ~ '^h.*o$';<\/code><\/td>TRUE<\/td><\/tr>
!~<\/code><\/td>\u53cd\u5411\u6b63\u5219\u5339\u914d<\/td>SELECT 'hello' !~ '^h.*a$';<\/code><\/td>TRUE<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT 'PostgreSQL' || ' is awesome!';<\/code><\/pre>\n\n\n\n
\n\n\n\n
6. NULL \u76f8\u5173\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th><\/tr><\/thead>
IS NULL<\/code><\/td>\u5224\u65ad\u662f\u5426\u4e3a NULL<\/td>SELECT * FROM employees WHERE salary IS NULL;<\/code><\/td><\/tr>
IS NOT NULL<\/code><\/td>\u5224\u65ad\u662f\u5426\u4e0d\u4e3a NULL<\/td>SELECT * FROM employees WHERE salary IS NOT NULL;<\/code><\/td><\/tr>
COALESCE<\/code><\/td>\u9009\u62e9\u7b2c\u4e00\u4e2a\u975e NULL \u503c<\/td>SELECT COALESCE(NULL, 'default', 'fallback');<\/code><\/td><\/tr>
NULLIF<\/code><\/td>\u5982\u679c\u4e24\u4e2a\u503c\u76f8\u7b49\uff0c\u5219\u8fd4\u56de NULL\uff0c\u5426\u5219\u8fd4\u56de\u7b2c\u4e00\u4e2a\u503c<\/td>SELECT NULLIF(10, 10);<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT COALESCE(NULL, 'Fallback Value');  -- \u7ed3\u679c\uff1aFallback Value<\/code><\/pre>\n\n\n\n
\n\n\n\n
7. \u6570\u7ec4\u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
PostgreSQL \u652f\u6301\u6570\u7ec4\u8fd0\u7b97\u7b26\u3002<\/p>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th><\/tr><\/thead>
&&<\/code><\/td>\u662f\u5426\u6709\u91cd\u53e0<\/td>SELECT ARRAY[1,2,3] && ARRAY[3,4,5];<\/code><\/td><\/tr>
@><\/code><\/td>\u662f\u5426\u5305\u542b<\/td>SELECT ARRAY[1,2,3,4] @> ARRAY[2,3];<\/code><\/td><\/tr>
<@<\/code><\/td>\u662f\u5426\u88ab\u5305\u542b<\/td>SELECT ARRAY[2,3] <@ ARRAY[1,2,3,4];<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT ARRAY[1, 2, 3] @> ARRAY[2];  -- \u7ed3\u679c\uff1aTRUE<\/code><\/pre>\n\n\n\n
\n\n\n\n
8. JSON\/JSONB \u8fd0\u7b97\u7b26<\/strong><\/h2>\n\n\n\n
PostgreSQL \u63d0\u4f9b JSON \u76f8\u5173\u7684\u8fd0\u7b97\u7b26\u3002<\/p>\n\n\n\n
\u8fd0\u7b97\u7b26<\/th>\u63cf\u8ff0<\/th>\u793a\u4f8b<\/th><\/tr><\/thead>
-><\/code><\/td>\u63d0\u53d6 JSON \u5bf9\u8c61\u4e2d\u7684\u5b57\u6bb5<\/td>SELECT '{\"name\": \"Alice\"}'::json -> 'name';<\/code><\/td><\/tr>
->><\/code><\/td>\u63d0\u53d6 JSON \u5b57\u6bb5\u503c\u4e3a\u6587\u672c<\/td>SELECT '{\"name\": \"Alice\"}'::json ->> 'name';<\/code><\/td><\/tr>
#><\/code><\/td>\u63d0\u53d6 JSON \u8def\u5f84<\/td>SELECT '{\"person\": {\"name\": \"Bob\"}}'::json #> '{person, name}';<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u793a\u4f8b\uff1a<\/p>\n\n\n\n
SELECT '{\"name\": \"John\", \"age\": 30}'::jsonb -> 'name';  -- \u7ed3\u679c\uff1a\"John\"<\/code><\/pre>\n\n\n\n
\n\n\n\n
\u603b\u7ed3<\/strong><\/h2>\n\n\n\n
PostgreSQL \u63d0\u4f9b\u4e30\u5bcc\u7684\u8fd0\u7b97\u7b26\uff0c\u6db5\u76d6\uff1a<\/p>\n\n\n\n
    \n
  • \u6570\u5b66\u8fd0\u7b97\u7b26<\/strong> (+<\/code>, -<\/code>, *<\/code>, \/<\/code>, %<\/code>)<\/li>\n\n\n\n
  • \u6bd4\u8f83\u8fd0\u7b97\u7b26<\/strong> (=<\/code>, <><\/code>, <<\/code>, ><\/code>)<\/li>\n\n\n\n
  • \u903b\u8f91\u8fd0\u7b97\u7b26<\/strong> (AND<\/code>, OR<\/code>, NOT<\/code>)<\/li>\n\n\n\n
  • \u4f4d\u8fd0\u7b97\u7b26<\/strong> (&<\/code>, |<\/code>, #<\/code>)<\/li>\n\n\n\n
  • \u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26<\/strong> (||<\/code>, LIKE<\/code>, ~<\/code>)<\/li>\n\n\n\n
  • NULL \u5904\u7406<\/strong> (IS NULL<\/code>, COALESCE<\/code>)<\/li>\n\n\n\n
  • \u6570\u7ec4\u8fd0\u7b97\u7b26<\/strong> (@><\/code>, <@<\/code>)<\/li>\n\n\n\n
  • JSON \u8fd0\u7b97\u7b26<\/strong> (-><\/code>, ->><\/code>)<\/li>\n<\/ul>\n\n\n\n
    PostgreSQL \u8fd0\u7b97\u7b26\u975e\u5e38\u5f3a\u5927\uff0c\u53ef\u4ee5\u6ee1\u8db3\u5404\u79cd\u67e5\u8be2\u9700\u6c42\u3002\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u5728 PostgreSQL \u4e2d\uff0c\u8fd0\u7b97\u7b26\u7528\u4e8e\u6267\u884c\u5404\u79cd\u64cd\u4f5c\uff0c\u5982\u6570\u5b66\u8ba1\u7b97\u3001\u6bd4\u8f83\u3001\u903b\u8f91\u5224\u65ad\u3001\u5b57\u7b26\u4e32\u64cd\u4f5c\u7b49\u3002Postgre […]<\/p>\n","protected":false},"author":1,"featured_media":2614,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[78],"tags":[],"class_list":["post-2613","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-postgresql"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2613","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=2613"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2613\/revisions"}],"predecessor-version":[{"id":2615,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2613\/revisions\/2615"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media\/2614"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=2613"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=2613"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=2613"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}