【发布时间】：2015-10-17 23:17:32
【问题描述】：
我有created the database in SQL lite and improved the little program to handle it（列出、添加、删除记录）。此时，我正在尝试使用准备好的语句 step() 函数列出数据库中的内容。但是，我无法遍历数据库中的行和列。
我怀疑这是因为我没有正确处理这一行中的语句：
stmt:Sqlite.Statement = null
如果是这样，如何将主（init）函数的语句传递给子函数？
这是到目前为止的全部代码：
// Trying to do a cookbook program
// raw_imput for Genie included, compile with valac --pkg sqlite3 cookbook.gs
[indent=4]
uses Sqlite
def raw_input (query:string = ""):string
stdout.printf ("%s", query)
return stdin.read_line ()
init
db : Sqlite.Database? = null
if (Sqlite.Database.open ("cookbook.db3", out db) != Sqlite.OK)
stderr.printf ("Error: %d: %s \n", db.errcode (), db.errmsg ())
Process.exit (-1)
loop:bool = true
while loop = true
print "==================================================="
print " RECIPE DATABASE "
print " 1 - Show All Recipes"
print " 2 - Search for a recipe"
print " 3 - Show a Recipe"
print " 4 - Delete a recipe"
print " 5 - Add a recipe"
print " 6 - Print a recipe"
print " 0 - Exit"
print "==================================================="
response:string = raw_input("Enter a selection -> ")
if response == "1" // Show All Recipes
PrintAllRecipes()
else if response is "2" // Search for a recipe
pass
else if response is "3" //Show a Recipe
pass
else if response is "4"//Delete a recipe
pass
else if response is "5" //Add a recipe
pass
else if response is "6" //Print a recipe
pass
else if response is "0" //Exit
print "Goodbye"
Process.exit (-1)
else
print "Unrecognized command. Try again."
def PrintAllRecipes ()
print "%-5s%-30s%-20s%-30s", "Item", "Name", "Serves", "Source"
print "--------------------------------------------------------------------------------------"
stmt:Sqlite.Statement = null
param_position:int = stmt.bind_parameter_index ("$UID")
//assert (param_position > 0)
stmt.bind_int (param_position, 1)
cols:int = stmt.column_count ()
while stmt.step () == Sqlite.ROW
for i:int = 0 to cols
i++
col_name:string = stmt.column_name (i)
val:string = stmt.column_text (i)
type_id:int = stmt.column_type (i)
stdout.printf ("column: %s\n", col_name)
stdout.printf ("value: %s\n", val)
stdout.printf ("type: %d\n", type_id)
/* while stmt.step () == Sqlite.ROW
col_item:string = stmt.column_name (1)
col_name:string = stmt.column_name (2)
col_serves:string = stmt.column_name (3)
col_source:string = stmt.column_name (4)
print "%-5s%-30s%-20s%-30s", col_item, col_name, col_serves, col_source */
额外的问题是：
函数的定义应该在init之前还是之后？我注意到，如果我在初始化后离开所有这些，它们就不会被调用。但是通过在开头留下 raw_input，错误就消失了。
出于教学原因，我试图在一个类中定义 PrintAllRecipes()。但我最终让它对主程序“不可见”。
非常感谢，
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