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一些自定义 PostgreSQL 随机数据生成器 —— Some self-defined PostgreSQL random data generators

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标签:alpha   rate   ext   class   Fix   int   trunc   cas   rgb   

1. 生成随机整数 —— Generate a random integer

-- Function:
  -- Generate a random integer
 
-- Parameters:
  -- min_value: Minimum value
  -- max_value: Maximum value
create or replace function gen_random_int(min_value int default 1,  max_value int default 1000) returns int  as
$$
begin
    return min_value + round((max_value - min_value) * random());
end;
$$ language plpgsql;

select gen_random_int();
select gen_random_int(1,10);

 

2. 生成随机字母字符串 —— Generate a random alphabetical string

-- Function:
  -- Generate a random alphabetical string
 
-- Parameters:
  -- str_length: Length of the string
  -- letter_case: Case of letters. Values for option: lower, upper and mixed
create or replace function gen_random_alphabetical_string(str_length int default 10, letter_case text default lower) returns text as
$body$
begin
    if letter_case in (lower, upper, mixed) then
        return
        case letter_case 
            when lower then array_to_string(array(select substr(abcdefghijklmnopqrstuvwxyz,(ceil(random()*26))::int, 1) FROM generate_series(1, str_length)), ‘‘)
            when upper then array_to_string(array(select substr(ABCDEFGHIJKLMNOPQRSTUVWXYZ,(ceil(random()*26))::int, 1) FROM generate_series(1, str_length)), ‘‘)
            when mixed then array_to_string(array(select substr(ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,(ceil(random()*52))::int, 1) FROM generate_series(1, str_length)), ‘‘)
            else array_to_string(array(select substr(ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,(ceil(random()*52))::int, 1) FROM generate_series(1, str_length)), ‘‘)
       end;
    else
        RAISE EXCEPTION value % for parameter % is not recognized, letter_case, letter_case
        Using Hint = Use "lower", "upper" or "mixed". The default value is "lower", ERRCODE =22023;
    end if;
end;
$body$
language plpgsql volatile;

 

select gen_random_alphabetical_string(10);
select gen_random_alphabetical_string(‘lower‘);

 

3. 生成随机字符串 —— Generate a random alphanumeric string

-- Function:
  -- Generate a random alphanumeric string
 
-- Parameters:
  -- str_length: Length of the string
create or replace function gen_random_string(str_length int default 10) returns text as
$body$
    select array_to_string(array(select substr(0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,(ceil(random()*62))::int, 1) FROM generate_series(1, $1)), ‘‘);
$body$
language sql volatile;


select gen_random_string(10)

 

4. 生成随机时间戳 —— Generate a random timestamp

 -- Function:
 -- Generate a random timestamp
-- Parameters: -- start_time: Lower bound of the time -- end_time: Upper bound of the time create or replace function gen_random_timestamp(start_time timestamp default date_trunc(year, now()), end_time timestamp default now()) returns timestamp as $$ begin return start_time + round((extract(epoch from end_time)- extract(epoch from start_time))* random()) * interval 1 second; end; $$ language plpgsql;


select gen_random_timestamp();
select gen_random_timestamp(‘2017-10-22 10:05:33‘,‘2017-10-22 10:05:35‘);

 

5.  生成随机整型数组 —— Generate a random integer array

-- Function:
  -- Generate a random integer array
 
-- Parameters:
  -- max_value: Maximum value of the elements
  -- max_length: Maximum length of the array
  -- fixed_length: Whether the length of array is fixed. If it is true, the length of array will match max_length.
create or replace function gen_random_int_array(max_value int default 1000, max_length int default 10, fixed_length bool default true ) returns int[] as
$$
begin
    return case when not fixed_length then array(select ceil(random()*max_value)::int from generate_series(1,ceil(random()*max_length)::int)) else array(select ceil(random()*max_value)::int from generate_series(1,max_length)) end ;
end;
$$ LANGUAGE plpgsql

 

6.  生成随机字符串数组 —— Generate a random string array

-- Function:
  -- Generate a random string array
 
-- Parameters:
  -- str_length: Length of string
  -- max_length: Maximum length of the array
  -- fixed_length: Whether the length of array is fixed. If it is true, the length of array will match max_length.
create or replace function gen_random_string_array(str_length int default 10, max_length int default 10, fixed_length bool default TRUE ) returns text[] as
$$
declare v_array text[];
declare v_i int;
begin
     v_array := array[]::text[];
     if fixed_length then
        for v_i in select generate_series(1, max_length) loop
            v_array := array_append(v_array,array_to_string(array(select substr(0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,(ceil(random()*62))::int, 1) FROM generate_series(1, str_length)), ‘‘));
        end loop;
     else
        for v_i in select generate_series(1,ceil(random()* max_length)::int) loop
           v_array := array_append(v_array,array_to_string(array(select substr(0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,(ceil(random()*62))::int, 1) FROM generate_series(1, str_length)), ‘‘));
        end loop;
     end if;
 
    return  v_array;
end;
$$ language plpgsql

 

select gen_random_string_array()
select gen_random_string_array(10,5,true);

 

7.  从整数数组中随机选择一个元素 —— Randomly select one element from an integer array

-- Function:
-- Randomly select one element from an integer array
create or replace function select_random_one(list int[]) returns int as
$$
declare v_length int := array_length(list, 1);
begin
    return list[1+round((v_length-1)*random())];
end;
$$ language plpgsql;

 

select select_random_one(array[1,2,3,4]);

 

8. 从字符串数组中随机选择一个元素 —— Randomly select one element from an string-array

-- Function:
-- Randomly select one element from an string-array
 
-- str_length: Length of string
create or replace function select_random_one(list text[]) returns text as
$$
declare v_length int := array_length(list, 1);
begin
    return list[1+round((v_length-1)*random())];
end;
$$ language plpgsql;

 

select select_random_one(array[‘abc‘,‘def‘,‘ghi‘]);

 

9.  随机生成汉字字符串 —— Generate a random Chinese string

-- Generate a random Chinese string
create or replace function gen_ramdom_chinese_string(str_length int) returns text as
$$
declare
   my_char char; 
   char_string varchar := ‘‘;
   i int := 0;
begin
    while (i < str_length) loop  -- chinese 19968..40869
        my_char = chr(19968 + round(20901 * random())::int);
        char_string := char_string || my_char;
        i = i + 1;
    end loop;
    return char_string;
end;
$$ language plpgsql;

 

10. 随机手机号码生成器,11位手机号 —— Generate a random mobile number

-- Generate a random mobile number
create or replace function gen_random_mobile_number() returns text as
$body$
    select 1 || string_agg(col,‘‘) from (select substr(0123456789,(ceil(random()*10))::int, 1) as col FROM generate_series(1, 10)) result;
$body$
language sql volatile;

 

select gen_random_mobile_number();

 

一些自定义 PostgreSQL 随机数据生成器 —— Some self-defined PostgreSQL random data generators

标签:alpha   rate   ext   class   Fix   int   trunc   cas   rgb   

原文地址:https://www.cnblogs.com/xianghuaqiang/p/14425274.html

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