通过ODBC C ++将带有日期时间的记录插入SQL Server 2014的问题

Question

I have a simple c++ code to insert a record in SQL Server 2014 via ODBC. It works fine with varchar fields, but it does not work with datetime field.

SQLCHAR buf[64];
SQLLEN len;
SQLCHAR buf2[255];
SQLLEN len2;
SQLLEN len3;
double f;
rc = SQLBindParameter(hstmt, 1, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_TYPE_TIMESTAMP, 19, 0, (SQLCHAR*)buf, 0, &len);
rc = SQLBindParameter(hstmt, 2, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_VARCHAR, 255, 0, (SQLCHAR*)buf2, 0, &len2);
rc = SQLBindParameter(hstmt, 3, SQL_PARAM_INPUT, SQL_C_FLOAT, SQL_FLOAT, 15, 0, &f, 0, &len3);
rc = SQLPrepare(hstmt, (SQLCHAR*)"insert into test(timepoint,strvalue,floatvalue) values (?,?,?)", SQL_NTS);

strcpy((char*)buf,"20171010 00:08:14");
len=strlen("20171017 00:08:14");
strcpy((char*)buf2,"simple string");
len2=strlen("simple string");
f=1.34e+8;

SQLSMALLINT NumParams;
SQLNumParams(hstmt, &NumParams);
rc = SQLExecute(hstmt);

Can anybody help to understand that is wrong? I've got always:

"22018:1:0:[Microsoft][ODBC SQL Server Driver]Invalid character value for cast specification\\n"

If I'm wrong here with my question, please give a hint which forum fits better. I've spent some days, but can't find the solution. For any help would be very appreciate.

Answer 1

SQL Server can cast various strings in different date formats to a real date implicitly, but you must be very careful how to use them:

There is the unseparated date format "yyyyMMdd", which cannot carry a time!

SELECT CAST('20170102' AS DATETIME) --2017-01-02 00:00:00.000

The most universal format is ISO8601 , which is yyyy-MM-ddTHH:mm:ss (beware of the the T in the middle and the usage of 24 hours format!)

SELECT CAST('2017-01-02T12:23:59' AS DATETIME) --2017-01-02 12:23:59.000

And - last but not least - there are three ODBC formats:

SELECT CAST({d'2017-01-02'} AS DATETIME)           --2017-01-02 00:00:00.000
SELECT CAST({t'23:35:51'} AS DATETIME)             --2018-01-19 23:35:51.000 (today!)
SELECT CAST({ts'2017-01-02 23:35:51'} AS DATETIME) --2017-01-02 23:35:51.000

And a last - important! - hint: Some formats work, but depend on the system's settings. This can work for you and pass all internal tests, but might break on a customer's machine:

SET LANGUAGE ENGLISH;
SELECT CAST('2017-01-02 23:35:51' AS DATETIME) -- Jan 2
SET LANGUAGE GERMAN;
SELECT CAST('2017-01-02 23:35:51' AS DATETIME) -- Feb 1