摘要
不建议在sql中使用json，但是json在sql中确实有很多灵活的使用，尤其是复杂查询，记录一下常见的使用情况
16版本下支持json
SQL Server 2016开始支持JSON数据类型，现在很多还是没有升级到这个版本，为了支持json，需要自己定义json处理函数
附上处理json的函数
CREATE FUNCTION [dbo].[ParseJSON]( @json nvarchar(max) )
RETURNS @hierarchy table
(
object_id int NOT NULL, /* [0 -- Not an object] each list or object has an object id. This ties all elements to a parent. Lists are treated as objects here */
parent_id int NOT NULL, /* [0 -- Root] if the element has a parent then it is in this column. The document is the ultimate parent, so you can get the structure from recursing from the document */
name nvarchar(2000), /* the name of the object */
stringvalue nvarchar(4000) NOT NULL, /*the string representation of the value of the element. */
valuetype nvarchar(100) NOT NULL, /* the declared type of the value represented as a string in stringvalue*/
bigintvalue bigint,
boolvalue bit
)
AS
BEGIN
DECLARE
@firstobject int, --the index of the first open bracket found in the JSON string
@opendelimiter int, --the index of the next open bracket found in the JSON string
@nextopendelimiter int,--the index of subsequent open bracket found in the JSON string
@nextclosedelimiter int,--the index of subsequent close bracket found in the JSON string
@type nvarchar(10),--whether it denotes an object or an array
@nextclosedelimiterChar CHAR(1),--either a '}' or a ']'
@contents nvarchar(MAX), --the unparsed contents of the bracketed expression
@start int, --index of the start of the token that you are parsing
@end int,--index of the end of the token that you are parsing
@param int,--the parameter at the end of the next Object/Array token
@endofname int,--the index of the start of the parameter at end of Object/Array token
@token nvarchar(4000),--either a string or object
@value nvarchar(MAX), -- the value as a string
@name nvarchar(200), --the name as a string
@parent_id int,--the next parent ID to allocate
@lenjson int,--the current length of the JSON String
@characters NCHAR(62),--used to convert hex to decimal
@result BIGINT,--the value of the hex symbol being parsed
@index SMALLINT,--used for parsing the hex value
@escape int; --the index of the next escape character
/* in this temporary table we keep all strings, even the names of the elements, since they are 'escaped'
* in a different way, and may contain, unescaped, brackets denoting objects or lists. These are replaced in
* the JSON string by tokens representing the string
*/
DECLARE @strings table
(
string_id int IDENTITY(1, 1),
stringvalue nvarchar(MAX)
)
/* initialise the characters to convert hex to ascii */
SET @characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
SET @parent_id = 0;
/* firstly we process all strings. This is done because [{} and ] aren't escaped in strings, which complicates an iterative parse. */
WHILE 1 = 1 /* forever until there is nothing more to do */
BEGIN
SET @start = PATINDEX('%[^a-zA-Z]["]%', @json collate SQL_Latin1_General_CP850_Bin); /* next delimited string */
IF @start = 0 BREAK; /*no more so drop through the WHILE loop */
IF SUBSTRING(@json, @start+1, 1) = '"'
BEGIN /* Delimited name */
SET @start = @start+1;
SET @end = PATINDEX('%[^\]["]%', RIGHT(@json, LEN(@json+'|')-@start) collate SQL_Latin1_General_CP850_Bin);
END
IF @end = 0 /*no end delimiter to last string*/
BREAK; /* no more */
SELECT @token = SUBSTRING(@json, @start+1, @end-1)
/* now put in the escaped control characters */
SELECT @token = REPLACE(@token, from_string, to_string)
FROM
(
SELECT '\"' AS from_string, '"' AS to_string
UNION ALL
SELECT '\\', '\'
UNION ALL
SELECT '\/', '/'
UNION ALL
SELECT '\b', CHAR(08)
UNION ALL
SELECT '\f', CHAR(12)
UNION ALL
SELECT '\n', CHAR(10)
UNION ALL
SELECT '\r', CHAR(13)
UNION ALL
SELECT '\t', CHAR(09)
) substitutions;
SET @result = 0;
SET @escape = 1;
/*Begin to take out any hex escape codes*/
WHILE @escape > 0
BEGIN
/* find the next hex escape sequence */
SET @index = 0;
SET @escape = PATINDEX('%\x[0-9a-f][0-9a-f][0-9a-f][0-9a-f]%', @token collate SQL_Latin1_General_CP850_Bin);
IF @escape > 0 /* if there is one */
BEGIN
WHILE @index < 4 /* there are always four digits to a \x sequence */
BEGIN
/* determine its value */
SET @result = @result + POWER(16, @index) * (CHARINDEX(SUBSTRING(@token, @escape + 2 + 3 - @index, 1), @characters) - 1);
SET @index = @index + 1;
END
/* and replace the hex sequence by its unicode value */
SET @token = STUFF(@token, @escape, 6, NCHAR(@result));
END
END
/* now store the string away */
INSERT INTO @strings (stringvalue) SELECT @token;
/* and replace the string with a token */
SET @json = STUFF(@json, @start, @end + 1, '@string' + CONVERT(nvarchar(5), @@identity));
END
/* all strings are now removed. Now we find the first leaf. */
WHILE 1 = 1 /* forever until there is nothing more to do */
BEGIN
SET @parent_id = @parent_id + 1;
/* find the first object or list by looking for the open bracket */
SET @firstobject = PATINDEX('%[{[[]%', @json collate SQL_Latin1_General_CP850_Bin); /*object or array*/
IF @firstobject = 0 BREAK;
IF (SUBSTRING(@json, @firstobject, 1) = '{')
SELECT @nextclosedelimiterChar = '}', @type = 'object';
ELSE
SELECT @nextclosedelimiterChar = ']', @type = 'array';
SET @opendelimiter = @firstobject;
WHILE 1 = 1 --find the innermost object or list...
BEGIN
SET @lenjson = LEN(@json+'|') - 1;
/* find the matching close-delimiter proceeding after the open-delimiter */
SET @nextclosedelimiter = CHARINDEX(@nextclosedelimiterChar, @json, @opendelimiter + 1);
/* is there an intervening open-delimiter of either type */
SET @nextopendelimiter = PATINDEX('%[{[[]%',RIGHT(@json, @lenjson-@opendelimiter) collate SQL_Latin1_General_CP850_Bin); /*object*/
IF @nextopendelimiter = 0 BREAK;
SET @nextopendelimiter = @nextopendelimiter + @opendelimiter;
IF @nextclosedelimiter < @nextopendelimiter BREAK;
IF SUBSTRING(@json, @nextopendelimiter, 1) = '{'
SELECT @nextclosedelimiterChar = '}', @type = 'object';
ELSE
SELECT @nextclosedelimiterChar = ']', @type = 'array';
SET @opendelimiter = @nextopendelimiter;
END
/* and parse out the list or name/value pairs */
SET @contents = SUBSTRING(@json, @opendelimiter+1, @nextclosedelimiter-@opendelimiter - 1);
SET @json = STUFF(@json, @opendelimiter, @nextclosedelimiter - @opendelimiter + 1, '@' + @type + CONVERT(nvarchar(5), @parent_id));
WHILE (PATINDEX('%[A-Za-z0-9@+.e]%', @contents collate SQL_Latin1_General_CP850_Bin)) < > 0
BEGIN /* WHILE PATINDEX */
IF @type = 'object' /*it will be a 0-n list containing a string followed by a string, number,boolean, or null*/
BEGIN
SET @end = CHARINDEX(':', ' '+@contents); /*if there is anything, it will be a string-based name.*/
SET @start = PATINDEX('%[^A-Za-z@][@]%', ' ' + @contents collate SQL_Latin1_General_CP850_Bin); /*AAAAAAAA*/
SET @token = SUBSTRING(' '+@contents, @start + 1, @end - @start - 1);
SET @endofname = PATINDEX('%[0-9]%', @token collate SQL_Latin1_General_CP850_Bin);
SET @param = RIGHT(@token, LEN(@token)-@endofname + 1);
SET @token = LEFT(@token, @endofname - 1);
SET @contents = RIGHT(' ' + @contents, LEN(' ' + @contents + '|') - @end - 1);
SELECT @name = stringvalue FROM @strings WHERE string_id = @param; /*fetch the name*/
END
ELSE
BEGIN
SET @name = null;
END
SET @end = CHARINDEX(',', @contents); /*a string-token, object-token, list-token, number,boolean, or null*/
IF @end = 0
SET @end = PATINDEX('%[A-Za-z0-9@+.e][^A-Za-z0-9@+.e]%', @contents+' ' collate SQL_Latin1_General_CP850_Bin) + 1;
SET @start = PATINDEX('%[^A-Za-z0-9@+.e][A-Za-z0-9@+.e]%', ' ' + @contents collate SQL_Latin1_General_CP850_Bin);
/*select @start,@end, LEN(@contents+'|'), @contents */
SET @value = RTRIM(SUBSTRING(@contents, @start, @end-@start));
SET @contents = RIGHT(@contents + ' ', LEN(@contents+'|') - @end);
IF SUBSTRING(@value, 1, 7) = '@object'
INSERT INTO @hierarchy (name, parent_id, stringvalue, object_id, valuetype)
SELECT @name, @parent_id, SUBSTRING(@value, 8, 5), SUBSTRING(@value, 8, 5), 'object';
ELSE
IF SUBSTRING(@value, 1, 6) = '@array'
INSERT INTO @hierarchy (name, parent_id, stringvalue, object_id, valuetype)
SELECT @name, @parent_id, SUBSTRING(@value, 7, 5), SUBSTRING(@value, 7, 5), 'array';
ELSE
IF SUBSTRING(@value, 1, 7) = '@string'
INSERT INTO @hierarchy (name, parent_id, stringvalue, valuetype, object_id)
SELECT @name, @parent_id, stringvalue, 'string', 0
FROM @strings
WHERE string_id = SUBSTRING(@value, 8, 5);
ELSE
IF @value IN ('true', 'false')
INSERT INTO @hierarchy (name, parent_id, stringvalue, valuetype, object_id, boolvalue)
SELECT @name, @parent_id, @value, 'boolean', 0, CASE @value WHEN 'true' THEN 1 ELSE 0 END;
ELSE
IF @value = 'null'
INSERT INTO @hierarchy (name, parent_id, stringvalue, valuetype, object_id)
SELECT @name, @parent_id, @value, 'null', 0;
ELSE
IF PATINDEX('%[^0-9]%', @value collate SQL_Latin1_General_CP850_Bin) > 0
INSERT INTO @hierarchy (name, parent_id, stringvalue, valuetype, object_id)
SELECT @name, @parent_id, @value, 'real', 0;
ELSE
INSERT INTO @hierarchy (name, parent_id, stringvalue, valuetype, object_id, bigintvalue)
SELECT @name, @parent_id, @value, 'bigint', 0, CONVERT(BIGINT,@value);
END /* WHILE PATINDEX */
END /* WHILE 1=1 forever until there is nothing more to do */
INSERT INTO @hierarchy (name, parent_id, stringvalue, object_id, valuetype)
SELECT '', 0, '', @parent_id - 1, @type;
RETURN;
END
用这个函数去处理json字符串，转成二维表，会有父子节点，数据类型等相关信息
declare @json varchar(max) = '{"data":{"name":"tom","code":"Tom","age":12}}'
select * from parseJSON(@json) where name = 'code'
表格json处理
遇到一个有意思的查询条件，是根据两个字段的组合来查询数据
例如公司+项目，传过来的是这样的json数据
[
{
"company":"alibaba",
"project":["A","B"]
},
{
"company":"tencent",
"project":["B","C"]
},
{
"company":"bytedance",
"project":["A","C"]
}
]
对于这样的查询刚开始的想法就是每个条件查出来后Union所有的查询结果，然而还需要分页，外面还需要再套一层，麻烦，就想着在数据库自己处理json的查询条件，将这些条件放到临时表里，直接关联主表就很方便了
还是需要先转一下json的格式，转成二维表
[
{
"company":"alibaba",
"project":"A"
},
{
"company":"alibaba",
"project":"B"
},
{
"company":"tencent",
"project":"B"
},
{
"company":"tencent",
"project":"C"
},
{
"company":"bytedance",
"project":"A"
},
{
"company":"bytedance",
"project":"C"
}
]
这样的数据parseJSON后的格式是这样的，还需要进行行列转换一下
转化之后就可以很清楚的看到表结构了，直接用主表去做关联就可以了，很方便
