操作文字資料

Snowflake 的資料型別與函式

Jake Roach

Field Data Engineer

計算字串的 LENGTH

LENGTH(<field>)

SELECT
    song_name,
    LENGTH(song_name) AS characters
FROM MUSIC.songs;

       song_name    |  characters
   ---------------- | -----------
     Levon          |      5     
     Tiny Dancer    |      11
     Rocket Man     |      10

LENGTH 會回傳文字字串的字元數

會計入空白
VARCHAR、TEXT、STRING 等皆可用
LEN 等同於 LENGTH

TRIM

從文字值的開頭與結尾移除字元

最常用來去除空白
不分大小寫
有對應的 LTRIM 與 RTRIM

SELECT
    <field>,

    -- Remove characters at the
    -- beginning or end of the column
    TRIM(<1>, <2>)

FROM ...;

<1>：要進行裁剪的欄位或值

<2>：選填，要自開頭或結尾移除的樣式；未指定則為 ' '（空白）

TRIM

SELECT
    song_long_name,
    TRIM(song_long_name, '(Remastered)') AS trimmed_song_name
FROM MUSIC.songs;

TRIM(song_long_name, '(Remastered)')

                song_long_name          |     trimmed_song_name
           ---------------------------- | --------------------------
             (Remastered) Piano Man     |      Piano Man
             Ticking (Remastered)       |      Ticking
             Come Sail Away             |      Come Sail Away

SPLIT

依分隔符將文字切成值的陣列

回傳型別為 ARRAY
可用中括號標記法擷取值

<1>：要 SPLIT 的欄位

<2>：用來分割的分隔符

SELECT
    <field>,

    -- SPLIT the field, use bracket-
    -- notation to retrieve first chunk
    SPLIT(<1>, <2>),
    SPLIT(<1>, <2>)[X]

FROM ...;

       Math,Science,Art,Reading
                 ...
 ['Math', 'Science', 'Art', 'Reading']

SPLIT

SELECT
    collaborators,


    SPLIT(collaborators, ',') AS all_collaborators,

    SPLIT(collaborators, ',')[0] AS primary_artist  -- Return the first collaborator


FROM MUSIC.songs;

          collaborators       |          all_collaborators         |  primary_artist
   -------------------------- | ---------------------------------- | ---------------
   Queen, David Bowie         |  ['Queen', ' David Bowie']         |  Queen
   Elton John, Kiki Dee       |  ['Elton John', ' Kiki Dee']       |  Elton John
   Carly Simon, James Taylor  |  ['Carly Simon', ' James Taylor']  |  Carly Simon

CONCAT

SELECT
    <field>,
    <another-field>,
    <third-field>,

    CONCAT(
        <field>, 
        <another-field>,
        ' ',
        <third-field>
    )

FROM ...;

可將兩個以上的文字值接起來

值的數量不拘，以 , 分隔
需要自行插入空白字元
常用於合併名字與姓氏

CONCAT

SELECT
    song_name, artist_name,

    -- Concatenate three text values together
    CONCAT(song_name, ' is written by ', artist_name) AS description

FROM MUSIC.songs;

      song_name    |   artist_name  |         description        
 ----------------- | -------------- | --------------------------------------------
 Night Moves       |  Bob Seger     |  Night Moves is written by Bob Seger
 Cracklin' Rosie   |  Neal Diamond  |  Cracklin' Rosie is written by Neal Diamond

一起來練習吧！

Snowflake 的資料型別與函式