将数据写入mysql - C/C++ / C语言

c语言操作mysql数据库 
定义一个整型变量a；如何将a的值写回数据库
query = "update test.user set score=’50‘ where id='lisi' ";
这样可以 但我想将50改成变量a的值 该怎么修改

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友情支持,up~up~up~!!

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char query[300];
snprintf(query,sizeof(query), "update test.user set score='%d' where id=\"%s\" " , a, "lisi" );

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char query[300];
int score = 50;
char id[50] = "lisi";
sprintf(query, "update test.user set score='%d' where id='%s'" , score, id);