sqlite3StrAccumInit()函数
void sqlite3StrAccumInit(StrAccum *p, char *zBase, int n, int mx){
p->zText = p->zBase = zBase;
p->db = 0;
p->nChar = 0;
p->nAlloc = n;
p->mxAlloc = mx;
p->useMalloc = 1;
p->tooBig = 0;
p->mallocFailed = 0;
}
功能：这个函数用于初始化一个字符累加器。