unixODBC/FreeTDS 结果被截断为 255 个字符

UPDATE 2

我打开了跟踪并运行了示例查询。这是痕迹。我确实看到了Strlen Or Ind = 0x7fff9c84ee88 -> 255声明。indicator变量定义为SQLLEN indicator;这是否未正确初始化？

[ODBC][22407][1379343424.503572][__handles.c][450]
        Exit:[SQL_SUCCESS]
            Environment = 0x14f8160
[ODBC][22407][1379343424.503627][SQLSetEnvAttr.c][182]
        Entry:            
            Environment = 0x14f8160            
            Attribute = SQL_ATTR_ODBC_VERSION            
            Value = 0x3            
            StrLen = 0
[ODBC][22407][1379343424.503654][SQLSetEnvAttr.c][349]
        Exit:[SQL_SUCCESS]
[ODBC][22407][1379343424.503678][SQLAllocHandle.c][364]
        Entry:
            Handle Type = 2
            Input Handle = 0x14f8160
[ODBC][22407][1379343424.503707][SQLAllocHandle.c][482]
        Exit:[SQL_SUCCESS]
            Output Handle = 0x14f8a90
[ODBC][22407][1379343424.503745][SQLDriverConnect.c][688]
        Entry:            
            Connection = 0x14f8a90            
            Window Hdl = (nil)            
            Str In = [DSN=MyDB;UID=MyUID;][length = 15 (SQL_NTS)]            
            Str Out = 0x7fff9c84cc80            
            Str Out Max = 2048            
            Str Out Ptr = (nil)            
            Completion = 1
        UNICODE Using encoding ASCII 'ISO8859-1' and UNICODE 'UCS-2LE'
[ODBC][22407][1379343424.523244][SQLDriverConnect.c][1497]
        Exit:[SQL_SUCCESS]                    
            Connection Out [[DSN=MyDB;UID=MyUID;][length = 15 (SQL_NTS)]]
[ODBC][22407][1379343424.523297][SQLAllocHandle.c][529]
        Entry:
            Handle Type = 3
            Input Handle = 0x14f8a90
[ODBC][22407][1379343424.523343][SQLAllocHandle.c][1064]
        Exit:[SQL_SUCCESS]
            Output Handle = 0x1526b40
[ODBC][22407][1379343424.523377][SQLExecDirect.c][236]
        Entry:            
            Statement = 0x1526b40            
            SQL = [SELECT '123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890...][length = 309 (SQL_NTS)]
[ODBC][22407][1379343424.523948][SQLExecDirect.c][499]
        Exit:[SQL_SUCCESS]
[ODBC][22407][1379343424.523982][SQLNumResultCols.c][152]
        Entry:            
            Statement = 0x1526b40            
            Column Count = 0x7fff9c84eeae
[ODBC][22407][1379343424.524005][SQLNumResultCols.c][244]
        Exit:[SQL_SUCCESS]                
            Count = 0x7fff9c84eeae -> 1
[ODBC][22407][1379343424.524030][SQLFetch.c][158]
        Entry:            
            Statement = 0x1526b40
[ODBC][22407][1379343424.524056][SQLFetch.c][340]
        Exit:[SQL_SUCCESS]
[ODBC][22407][1379343424.524084][SQLGetData.c][233]
        Entry:            
            Statement = 0x1526b40            
            Column Number = 1            
            Target Type = 1 SQL_CHAR            
            Buffer Length = 5000            
            Target Value = 0x7fff9c84da90            
            StrLen Or Ind = 0x7fff9c84ee88
[ODBC][22407][1379343424.524115][SQLGetData.c][497]
        Exit:[SQL_SUCCESS]                
            Buffer = [12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678]                
            Strlen Or Ind = 0x7fff9c84ee88 -> 255
[ODBC][22407][1379343424.524142][SQLColAttribute.c][286]
        Entry:            
            Statement = 0x1526b40            
            Column Number = 1            
            Field Identifier = SQL_DESC_NAME            
            Character Attr = 0x7fff9c84ee20            
            Buffer Length = 100            
            String Length = 0x7fff9c84ee86            
            Numeric Attribute = (nil)
[ODBC][22407][1379343424.524167][SQLColAttribute.c][657]
        Exit:[SQL_SUCCESS]
[ODBC][22407][1379343424.524229][SQLFetch.c][158]
        Entry:            
            Statement = 0x1526b40
[ODBC][22407][1379343424.524257][SQLFetch.c][340]
        Exit:[SQL_NO_DATA]
[ODBC][22407][1379343424.524321][SQLDisconnect.c][204]
        Entry:            
            Connection = 0x14f8a90
[ODBC][22407][1379343424.524375][SQLDisconnect.c][341]
        Exit:[SQL_SUCCESS]
[ODBC][22407][1379343424.524415][SQLFreeHandle.c][279]
        Entry:
            Handle Type = 2
            Input Handle = 0x14f8a90
[ODBC][22407][1379343424.524438][SQLFreeHandle.c][330]
        Exit:[SQL_SUCCESS]
[ODBC][22407][1379343424.524463][SQLFreeHandle.c][212]
        Entry:
            Handle Type = 1
            Input Handle = 0x14f8160

更新我进一步调查了我的C++计划。我现在看到查询结果在调用

data_ret = SQLGetData(stmt, i, SQL_C_CHAR, buf, sizeof(buf), &indicator);

buf 的长度足够，data_ret为零（成功）。我是否滥用了SQLGetData，或者它是否有一些我不知道的行为？

我见过其他人有类似的问题，但我还没有完全解决它。如果我查询一个长字符串，它会被截断为 255 个字符。我正在使用unixODBC和FreeTDS从Linux机器上的bash脚本查询SQL Server DB。

我通过把

[FreeTDS]
Description = v0.91 with protocol v7.2
Driver = /usr/lib64/libtdsodbc.so.0

在模板中并运行

odbcinst -i -d -f tds.driver.template

然后我把

[MyDB]
Driver = FreeTDS
Description = Database Description
Trace = No
Server = <serverIP>
Port = 1433
Database = <myDB>
UID = <myUID>

在模板中并运行

odbcinst -i -s -f tds.datasource.template

我试过这个答案，但我一定做错了什么。任何建议不胜感激。