一:理论 oracle 截取字符(substr),检索字符位置(instr) case when then else end语句使用 收藏 常用函数:substr和instr 1.SUBSTR(string,start_position,[length]) 求子字符串,返回字符串 解释:string 元字符串 start_position 开始位置(从0开始) length 可选项,子字符串的个数 For example: substr("ABCDEFG", ...
SELECTCASEatttypidWHEN21/*int2*/THEN16WHEN23/*int4*/THEN32WHEN20/*int8*/THEN64WHEN1700/*numeric*/THENCASEWHENatttypmod=-1THENnullELSE((atttypmod-4)>>16)&65535--calculate the precisionENDWHEN700/*float4*/THEN24/*FLT_MANT_DIG*/WHEN701/*float8*/THEN53/*DBL_MANT_DIG*/ELSEnullENDA...
CREATE TABLEpublic.example_tbl(id INT NOTNULL,notes TEXTNULL);SET ROLE none;在 psql 中,使用“describe”元命令:1\d 正如我们所见,表的所有者被设置为user1,因为该角色创建了它。 \d中的元命令是在幕后psql 执行以下查询,向我们展示关系列表(包括我们创建的表)以及谁拥有每个关系。 SELECT n.nspname as...
LOOP -- some computations IF count > 0 THEN EXIT; -- exit loop END IF; END LOOP; LOOP -- some computations EXIT WHEN count > 0; -- same result as previous example END LOOP; <> BEGIN -- some computations IF stocks > 100000 THEN EXIT ablock; -- causes exit from the BEGIN block...
* for example. * 5. Now we have a minimally valid node that can behave correctly * when told to reset or delete itself. We link the node to its * parent (if any), making the node part of the context tree. * 6. We return to the context-type-specific routine, which finishes ...
as further described below. When choosing how to partition your table, it’s also important to consider what changes may occur in the future. For example, if you choose to have one partition per customer and you currently have a small number of large customers, consider the implications if ...
DO $$ BEGIN LOOP INSERT INTO http_request ( site_id, ingest_time, url, request_country, ip_address, status_code, response_time_msec ) VALUES ( trunc(random()*32), clock_timestamp(), concat('http://example.com/', md5(random()::text)), ('{China,India,USA,Indonesia}'::text[])...
CREATE TABLE public.example_tbl ( id INT NOT NULL, notes TEXT NULL SET ROLE none; 在psql 中,使用“describe”元命令: 1 \d 在一个干净的数据库上,将显示表对象的拥有者(如果你的数据库中有其他对象,你可能会得到额外的输出行。): 正如我们所见,表的所有者被设置为user1,因为该角色创建了它。
Example 4-1 demonstrates how to use pgScript record variables and loops to build a cross tab table using the lu_fact_types table we create in Example 6-7. It creates an empty table called census.hisp_pop with numeric columns of hispanic_or_latino, white_alone, black_or_african_american...
For example, you can choose from features like point-in-time recovery, write-ahead logging, granular access controls, tablespaces, nested transactions, online backups, and multiversion concurrency control. Reliability and compliance Decades of development have helped make PostgreSQL extremely fault ...