String_agg (transact-sql)
Содержание:
SQL References
SQL Keywords
ADD
ADD CONSTRAINT
ALTER
ALTER COLUMN
ALTER TABLE
ALL
AND
ANY
AS
ASC
BACKUP DATABASE
BETWEEN
CASE
CHECK
COLUMN
CONSTRAINT
CREATE
CREATE DATABASE
CREATE INDEX
CREATE OR REPLACE VIEW
CREATE TABLE
CREATE PROCEDURE
CREATE UNIQUE INDEX
CREATE VIEW
DATABASE
DEFAULT
DELETE
DESC
DISTINCT
DROP
DROP COLUMN
DROP CONSTRAINT
DROP DATABASE
DROP DEFAULT
DROP INDEX
DROP TABLE
DROP VIEW
EXEC
EXISTS
FOREIGN KEY
FROM
FULL OUTER JOIN
GROUP BY
HAVING
IN
INDEX
INNER JOIN
INSERT INTO
INSERT INTO SELECT
IS NULL
IS NOT NULL
JOIN
LEFT JOIN
LIKE
LIMIT
NOT
NOT NULL
OR
ORDER BY
OUTER JOIN
PRIMARY KEY
PROCEDURE
RIGHT JOIN
ROWNUM
SELECT
SELECT DISTINCT
SELECT INTO
SELECT TOP
SET
TABLE
TOP
TRUNCATE TABLE
UNION
UNION ALL
UNIQUE
UPDATE
VALUES
VIEW
WHERE
MySQL Functions
String Functions
ASCII
CHAR_LENGTH
CHARACTER_LENGTH
CONCAT
CONCAT_WS
FIELD
FIND_IN_SET
FORMAT
INSERT
INSTR
LCASE
LEFT
LENGTH
LOCATE
LOWER
LPAD
LTRIM
MID
POSITION
REPEAT
REPLACE
REVERSE
RIGHT
RPAD
RTRIM
SPACE
STRCMP
SUBSTR
SUBSTRING
SUBSTRING_INDEX
TRIM
UCASE
UPPER
Numeric Functions
ABS
ACOS
ASIN
ATAN
ATAN2
AVG
CEIL
CEILING
COS
COT
COUNT
DEGREES
DIV
EXP
FLOOR
GREATEST
LEAST
LN
LOG
LOG10
LOG2
MAX
MIN
MOD
PI
POW
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SUM
TAN
TRUNCATE
Date Functions
ADDDATE
ADDTIME
CURDATE
CURRENT_DATE
CURRENT_TIME
CURRENT_TIMESTAMP
CURTIME
DATE
DATEDIFF
DATE_ADD
DATE_FORMAT
DATE_SUB
DAY
DAYNAME
DAYOFMONTH
DAYOFWEEK
DAYOFYEAR
EXTRACT
FROM_DAYS
HOUR
LAST_DAY
LOCALTIME
LOCALTIMESTAMP
MAKEDATE
MAKETIME
MICROSECOND
MINUTE
MONTH
MONTHNAME
NOW
PERIOD_ADD
PERIOD_DIFF
QUARTER
SECOND
SEC_TO_TIME
STR_TO_DATE
SUBDATE
SUBTIME
SYSDATE
TIME
TIME_FORMAT
TIME_TO_SEC
TIMEDIFF
TIMESTAMP
TO_DAYS
WEEK
WEEKDAY
WEEKOFYEAR
YEAR
YEARWEEK
Advanced Functions
BIN
BINARY
CASE
CAST
COALESCE
CONNECTION_ID
CONV
CONVERT
CURRENT_USER
DATABASE
IF
IFNULL
ISNULL
LAST_INSERT_ID
NULLIF
SESSION_USER
SYSTEM_USER
USER
VERSION
SQL Server Functions
String Functions
ASCII
CHAR
CHARINDEX
CONCAT
Concat with +
CONCAT_WS
DATALENGTH
DIFFERENCE
FORMAT
LEFT
LEN
LOWER
LTRIM
NCHAR
PATINDEX
QUOTENAME
REPLACE
REPLICATE
REVERSE
RIGHT
RTRIM
SOUNDEX
SPACE
STR
STUFF
SUBSTRING
TRANSLATE
TRIM
UNICODE
UPPER
Numeric Functions
ABS
ACOS
ASIN
ATAN
ATN2
AVG
CEILING
COUNT
COS
COT
DEGREES
EXP
FLOOR
LOG
LOG10
MAX
MIN
PI
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SQUARE
SUM
TAN
Date Functions
CURRENT_TIMESTAMP
DATEADD
DATEDIFF
DATEFROMPARTS
DATENAME
DATEPART
DAY
GETDATE
GETUTCDATE
ISDATE
MONTH
SYSDATETIME
YEAR
Advanced Functions
CAST
COALESCE
CONVERT
CURRENT_USER
IIF
ISNULL
ISNUMERIC
NULLIF
SESSION_USER
SESSIONPROPERTY
SYSTEM_USER
USER_NAME
MS Access Functions
String Functions
Asc
Chr
Concat with &
CurDir
Format
InStr
InstrRev
LCase
Left
Len
LTrim
Mid
Replace
Right
RTrim
Space
Split
Str
StrComp
StrConv
StrReverse
Trim
UCase
Numeric Functions
Abs
Atn
Avg
Cos
Count
Exp
Fix
Format
Int
Max
Min
Randomize
Rnd
Round
Sgn
Sqr
Sum
Val
Date Functions
Date
DateAdd
DateDiff
DatePart
DateSerial
DateValue
Day
Format
Hour
Minute
Month
MonthName
Now
Second
Time
TimeSerial
TimeValue
Weekday
WeekdayName
Year
Other Functions
CurrentUser
Environ
IsDate
IsNull
IsNumeric
SQL Quick Ref
SQL References
SQL Keywords
ADD
ADD CONSTRAINT
ALTER
ALTER COLUMN
ALTER TABLE
ALL
AND
ANY
AS
ASC
BACKUP DATABASE
BETWEEN
CASE
CHECK
COLUMN
CONSTRAINT
CREATE
CREATE DATABASE
CREATE INDEX
CREATE OR REPLACE VIEW
CREATE TABLE
CREATE PROCEDURE
CREATE UNIQUE INDEX
CREATE VIEW
DATABASE
DEFAULT
DELETE
DESC
DISTINCT
DROP
DROP COLUMN
DROP CONSTRAINT
DROP DATABASE
DROP DEFAULT
DROP INDEX
DROP TABLE
DROP VIEW
EXEC
EXISTS
FOREIGN KEY
FROM
FULL OUTER JOIN
GROUP BY
HAVING
IN
INDEX
INNER JOIN
INSERT INTO
INSERT INTO SELECT
IS NULL
IS NOT NULL
JOIN
LEFT JOIN
LIKE
LIMIT
NOT
NOT NULL
OR
ORDER BY
OUTER JOIN
PRIMARY KEY
PROCEDURE
RIGHT JOIN
ROWNUM
SELECT
SELECT DISTINCT
SELECT INTO
SELECT TOP
SET
TABLE
TOP
TRUNCATE TABLE
UNION
UNION ALL
UNIQUE
UPDATE
VALUES
VIEW
WHERE
MySQL Functions
String Functions
ASCII
CHAR_LENGTH
CHARACTER_LENGTH
CONCAT
CONCAT_WS
FIELD
FIND_IN_SET
FORMAT
INSERT
INSTR
LCASE
LEFT
LENGTH
LOCATE
LOWER
LPAD
LTRIM
MID
POSITION
REPEAT
REPLACE
REVERSE
RIGHT
RPAD
RTRIM
SPACE
STRCMP
SUBSTR
SUBSTRING
SUBSTRING_INDEX
TRIM
UCASE
UPPER
Numeric Functions
ABS
ACOS
ASIN
ATAN
ATAN2
AVG
CEIL
CEILING
COS
COT
COUNT
DEGREES
DIV
EXP
FLOOR
GREATEST
LEAST
LN
LOG
LOG10
LOG2
MAX
MIN
MOD
PI
POW
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SUM
TAN
TRUNCATE
Date Functions
ADDDATE
ADDTIME
CURDATE
CURRENT_DATE
CURRENT_TIME
CURRENT_TIMESTAMP
CURTIME
DATE
DATEDIFF
DATE_ADD
DATE_FORMAT
DATE_SUB
DAY
DAYNAME
DAYOFMONTH
DAYOFWEEK
DAYOFYEAR
EXTRACT
FROM_DAYS
HOUR
LAST_DAY
LOCALTIME
LOCALTIMESTAMP
MAKEDATE
MAKETIME
MICROSECOND
MINUTE
MONTH
MONTHNAME
NOW
PERIOD_ADD
PERIOD_DIFF
QUARTER
SECOND
SEC_TO_TIME
STR_TO_DATE
SUBDATE
SUBTIME
SYSDATE
TIME
TIME_FORMAT
TIME_TO_SEC
TIMEDIFF
TIMESTAMP
TO_DAYS
WEEK
WEEKDAY
WEEKOFYEAR
YEAR
YEARWEEK
Advanced Functions
BIN
BINARY
CASE
CAST
COALESCE
CONNECTION_ID
CONV
CONVERT
CURRENT_USER
DATABASE
IF
IFNULL
ISNULL
LAST_INSERT_ID
NULLIF
SESSION_USER
SYSTEM_USER
USER
VERSION
SQL Server Functions
String Functions
ASCII
CHAR
CHARINDEX
CONCAT
Concat with +
CONCAT_WS
DATALENGTH
DIFFERENCE
FORMAT
LEFT
LEN
LOWER
LTRIM
NCHAR
PATINDEX
QUOTENAME
REPLACE
REPLICATE
REVERSE
RIGHT
RTRIM
SOUNDEX
SPACE
STR
STUFF
SUBSTRING
TRANSLATE
TRIM
UNICODE
UPPER
Numeric Functions
ABS
ACOS
ASIN
ATAN
ATN2
AVG
CEILING
COUNT
COS
COT
DEGREES
EXP
FLOOR
LOG
LOG10
MAX
MIN
PI
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SQUARE
SUM
TAN
Date Functions
CURRENT_TIMESTAMP
DATEADD
DATEDIFF
DATEFROMPARTS
DATENAME
DATEPART
DAY
GETDATE
GETUTCDATE
ISDATE
MONTH
SYSDATETIME
YEAR
Advanced Functions
CAST
COALESCE
CONVERT
CURRENT_USER
IIF
ISNULL
ISNUMERIC
NULLIF
SESSION_USER
SESSIONPROPERTY
SYSTEM_USER
USER_NAME
MS Access Functions
String Functions
Asc
Chr
Concat with &
CurDir
Format
InStr
InstrRev
LCase
Left
Len
LTrim
Mid
Replace
Right
RTrim
Space
Split
Str
StrComp
StrConv
StrReverse
Trim
UCase
Numeric Functions
Abs
Atn
Avg
Cos
Count
Exp
Fix
Format
Int
Max
Min
Randomize
Rnd
Round
Sgn
Sqr
Sum
Val
Date Functions
Date
DateAdd
DateDiff
DatePart
DateSerial
DateValue
Day
Format
Hour
Minute
Month
MonthName
Now
Second
Time
TimeSerial
TimeValue
Weekday
WeekdayName
Year
Other Functions
CurrentUser
Environ
IsDate
IsNull
IsNumeric
SQL Quick Ref
Summary
So far, we’ve seen several examples of the SUBSTRING function in SQL Server, the character functions that SQL server makes readily available for use, and how you can use them to manipulate string values in your database and in your result set. In this way it is helpful to make sure that the output of SQL query data is formatted according to the expectations or business requirement.
We also need to understand the importance of the data-set. It is always recommended to thoroughly validate the input value. There are multiple ways to transform the data using the T-SQL SUBSTRING function. In a few cases, it is possible to transform using other SQL string functions. In some cases, volume of data, performance, and SQL Server version defines the options one over the other.
That’s all for now. I hope you enjoyed this article on SQL string functions and the SQL Server SUBSTRING function in particular. Feel free to ask any questions in the comments below.
引數Arguments
expressionexpression這是 character、binary、text、ntext 或 image 運算式。Is a character, binary, text, ntext, or image expression.
startstart這是指定傳回之字元開始的整數或 bigint 運算式。Is an integer or bigint expression that specifies where the returned characters start. (編號是以 1 為基礎，這表示運算式中的第一個字元為 1)。(The numbering is 1 based, meaning that the first character in the expression is 1). 如果 start 小於 1，傳回的運算式將會從 expression 內指定的第一個字元開始。If start is less than 1, the returned expression will begin at the first character that is specified in expression. 在此情況下，傳回的字元數會是 start + length 的總和 -1 或是 0 (以最大值為準)。In this case, the number of characters that are returned is the largest value of either the sum of start + length- 1 or 0. 如果 start 大於值運算式中的字元數，則會傳回長度為零的運算式。If start is greater than the number of characters in the value expression, a zero-length expression is returned.
lengthlength這是一個正整數，或是指定將傳回之 expression 字元數的 bigint 運算式。Is a positive integer or bigint expression that specifies how many characters of the expression will be returned. 如果 length 是負數，則會產生錯誤並結束此陳述式。If length is negative, an error is generated and the statement is terminated. 如果 start 和 length 的總和大於 expression 中的字元數，則會傳回從 start 開始的整個值運算式。If the sum of start and length is greater than the number of characters in expression, the whole value expression beginning at start is returned.
SQL References
SQL Keywords
ADD
ADD CONSTRAINT
ALTER
ALTER COLUMN
ALTER TABLE
ALL
AND
ANY
AS
ASC
BACKUP DATABASE
BETWEEN
CASE
CHECK
COLUMN
CONSTRAINT
CREATE
CREATE DATABASE
CREATE INDEX
CREATE OR REPLACE VIEW
CREATE TABLE
CREATE PROCEDURE
CREATE UNIQUE INDEX
CREATE VIEW
DATABASE
DEFAULT
DELETE
DESC
DISTINCT
DROP
DROP COLUMN
DROP CONSTRAINT
DROP DATABASE
DROP DEFAULT
DROP INDEX
DROP TABLE
DROP VIEW
EXEC
EXISTS
FOREIGN KEY
FROM
FULL OUTER JOIN
GROUP BY
HAVING
IN
INDEX
INNER JOIN
INSERT INTO
INSERT INTO SELECT
IS NULL
IS NOT NULL
JOIN
LEFT JOIN
LIKE
LIMIT
NOT
NOT NULL
OR
ORDER BY
OUTER JOIN
PRIMARY KEY
PROCEDURE
RIGHT JOIN
ROWNUM
SELECT
SELECT DISTINCT
SELECT INTO
SELECT TOP
SET
TABLE
TOP
TRUNCATE TABLE
UNION
UNION ALL
UNIQUE
UPDATE
VALUES
VIEW
WHERE
MySQL Functions
String Functions
ASCII
CHAR_LENGTH
CHARACTER_LENGTH
CONCAT
CONCAT_WS
FIELD
FIND_IN_SET
FORMAT
INSERT
INSTR
LCASE
LEFT
LENGTH
LOCATE
LOWER
LPAD
LTRIM
MID
POSITION
REPEAT
REPLACE
REVERSE
RIGHT
RPAD
RTRIM
SPACE
STRCMP
SUBSTR
SUBSTRING
SUBSTRING_INDEX
TRIM
UCASE
UPPER
Numeric Functions
ABS
ACOS
ASIN
ATAN
ATAN2
AVG
CEIL
CEILING
COS
COT
COUNT
DEGREES
DIV
EXP
FLOOR
GREATEST
LEAST
LN
LOG
LOG10
LOG2
MAX
MIN
MOD
PI
POW
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SUM
TAN
TRUNCATE
Date Functions
ADDDATE
ADDTIME
CURDATE
CURRENT_DATE
CURRENT_TIME
CURRENT_TIMESTAMP
CURTIME
DATE
DATEDIFF
DATE_ADD
DATE_FORMAT
DATE_SUB
DAY
DAYNAME
DAYOFMONTH
DAYOFWEEK
DAYOFYEAR
EXTRACT
FROM_DAYS
HOUR
LAST_DAY
LOCALTIME
LOCALTIMESTAMP
MAKEDATE
MAKETIME
MICROSECOND
MINUTE
MONTH
MONTHNAME
NOW
PERIOD_ADD
PERIOD_DIFF
QUARTER
SECOND
SEC_TO_TIME
STR_TO_DATE
SUBDATE
SUBTIME
SYSDATE
TIME
TIME_FORMAT
TIME_TO_SEC
TIMEDIFF
TIMESTAMP
TO_DAYS
WEEK
WEEKDAY
WEEKOFYEAR
YEAR
YEARWEEK
Advanced Functions
BIN
BINARY
CASE
CAST
COALESCE
CONNECTION_ID
CONV
CONVERT
CURRENT_USER
DATABASE
IF
IFNULL
ISNULL
LAST_INSERT_ID
NULLIF
SESSION_USER
SYSTEM_USER
USER
VERSION
SQL Server Functions
String Functions
ASCII
CHAR
CHARINDEX
CONCAT
Concat with +
CONCAT_WS
DATALENGTH
DIFFERENCE
FORMAT
LEFT
LEN
LOWER
LTRIM
NCHAR
PATINDEX
QUOTENAME
REPLACE
REPLICATE
REVERSE
RIGHT
RTRIM
SOUNDEX
SPACE
STR
STUFF
SUBSTRING
TRANSLATE
TRIM
UNICODE
UPPER
Numeric Functions
ABS
ACOS
ASIN
ATAN
ATN2
AVG
CEILING
COUNT
COS
COT
DEGREES
EXP
FLOOR
LOG
LOG10
MAX
MIN
PI
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SQUARE
SUM
TAN
Date Functions
CURRENT_TIMESTAMP
DATEADD
DATEDIFF
DATEFROMPARTS
DATENAME
DATEPART
DAY
GETDATE
GETUTCDATE
ISDATE
MONTH
SYSDATETIME
YEAR
Advanced Functions
CAST
COALESCE
CONVERT
CURRENT_USER
IIF
ISNULL
ISNUMERIC
NULLIF
SESSION_USER
SESSIONPROPERTY
SYSTEM_USER
USER_NAME
MS Access Functions
String Functions
Asc
Chr
Concat with &
CurDir
Format
InStr
InstrRev
LCase
Left
Len
LTrim
Mid
Replace
Right
RTrim
Space
Split
Str
StrComp
StrConv
StrReverse
Trim
UCase
Numeric Functions
Abs
Atn
Avg
Cos
Count
Exp
Fix
Format
Int
Max
Min
Randomize
Rnd
Round
Sgn
Sqr
Sum
Val
Date Functions
Date
DateAdd
DateDiff
DatePart
DateSerial
DateValue
Day
Format
Hour
Minute
Month
MonthName
Now
Second
Time
TimeSerial
TimeValue
Weekday
WeekdayName
Year
Other Functions
CurrentUser
Environ
IsDate
IsNull
IsNumeric
SQL Quick Ref
Substring in C language using function
We create a function and pass it four arguments original string array, substring array, position, and length of the required substring. As we use call by reference, we do not need to return the substring array. See another code below in which we return a pointer to substring, which we create in our function using dynamic memory allocation.
#include <stdio.h> void substring(char , char, int, int); int main() { char string1000, sub1000; int position, length, c = ; printf(«Input a string\n»); gets(string); printf(«Enter the position and length of substring\n»); scanf(«%d%d», &position, &length); substring(string, sub, position, length); printf(«Required substring is \»%s\»\n», sub); return ;}// C substring function definitionvoid substring(char s, char sub, int p, int l) { int c = ; while (c < l) { subc = sp+c-1; c++; } subc = ‘\0’;}
範例Examples
A.A. 使用 SUBSTRING 與字元字串Using SUBSTRING with a character string
下列範例會顯示如何只傳回字元字串的一部分。The following example shows how to return only a part of a character string. 從 資料表，此查詢會傳回第一個資料行中的系統資料庫名稱、第二個資料行中的資料庫第一個字母，以及最後一個資料行中的第三和第四個字元。From the table, this query returns the system database names in the first column, the first letter of the database in the second column, and the third and fourth characters in the final column.
以下為結果集。Here is the result set.
| NAMEname | InitialInitial | ThirdAndFourthCharactersThirdAndFourthCharacters |
|---|---|---|
| mastermaster | mm | stst |
| tempdbtempdb | tt | mpmp |
| modelmodel | mm | dede |
| msdbmsdb | mm | dbdb |
以下是如何顯示字串常數 的第二、第三和第四個字元。Here is how to display the second, third, and fourth characters of the string constant .
以下為結果集。Here is the result set.
B.B. 使用 SUBSTRING 與 text、ntext 以及 image 資料Using SUBSTRING with text, ntext, and image data
注意
若要執行下列範例，您必須安裝 pubs 資料庫。To run the following examples, you must install the pubs database.
下列範例示範如何從 資料庫之 資料表的各個 text 和 image資料行傳回前 10 個字元。The following example shows how to return the first 10 characters from each of a text and image data column in the table of the database. text 資料會當成 varchar 傳回，且 image 資料會當成 varbinary 傳回。text data is returned as varchar, and image data is returned as varbinary.
以下為結果集。Here is the result set.
下列範例會顯示 text 和 ntext 資料的 SUBSTRING 效果。The following example shows the effect of SUBSTRING on both text and ntext data. 首先，這個範例會在名稱為 的 資料庫中，建立一份新的資料表。First, this example creates a new table in the database named . 其次，這個範例會從 資料行的前 80 個字元中，建立 資料表的 資料行，再加入 來作為第一個字元。Second, the example creates the column in the table from the first 80 characters of the column and adds an as the first character. 最後， 會擷取所有簽發者識別碼，以及 text 和 ntext 發行者資訊資料行的 。Lastly, an retrieves all publisher identification numbers and the of both the text and ntext publisher information columns.
