Add SQL abstraction layer

abstraction.lua

@@ -0,0 +1,102 @@
+local modname = minetest.get_current_modname()
+
+local thismod = _G[modname]
+
+---- Table creation & deletion
+
+function thismod.create_table_sql(name, params)
+  local lines = {}
+  for _, coldata in ipairs(params.columns) do
+    local line = (coldata.name or coldata[1]) .. ' ' .. (coldata.type or coldata[2])
+    if coldata.notnull then
+       line = line .. ' NOT NULL'
+    end
+    if coldata.autoincrement then
+      line = line .. ' AUTO_INCREMENT'
+    end
+    table.insert(lines, line)
+  end
+  table.insert(lines, 'PRIMARY KEY (' .. table.concat(params.pkey, ',') .. ')')
+  for fkeyname, fkeydata in pairs(params.fkeys or {}) do
+    table.insert(lines, 'FOREIGN KEY (' .. fkeyname .. ') REFERENCES ' .. fkeydata.table ..
+        '(' .. fkeydata.column .. ')')
+  end
+  for _, ucol in pairs(params.unique or {}) do
+    if type(ucol) == 'table' then
+      table.insert(lines, 'UNIQUE (' .. table.concat(ucol, ',') .. ')')
+    else
+      table.insert(lines, 'UNIQUE (' .. ucol .. ')')
+    end
+  end
+  return 'CREATE TABLE ' .. name .. ' (' .. table.concat(lines, ',') .. ')'
+end
+function thismod.create_table(name, params)
+  thismod.conn:query(thismod.create_table_sql(name, params))
+end
+
+function thismod.drop_table_sql(name)
+  return 'DROP TABLE ' .. name
+end
+function thismod.drop_table(name)
+  thismod.conn:query(thismod.drop_table_sql(name))
+end
+
+---- INSERT prepare
+
+function thismod.prepare_insert_sql(tablename, colnames)
+  local qmarks = {}
+  for i = 1, #colnames do
+    qmarks[i] = '?'
+  end
+  return 'INSERT INTO ' .. tablename .. '(' .. table.concat(colnames, ',') .. ') VALUES (' ..
+      table.concat(qmarks, ',') .. ')'
+end
+function thismod.prepare_insert(tablename, cols)
+  local colnames, coltypes = {}, {}
+  for _, col in ipairs(cols) do
+    table.insert(colnames, col.name or col[1])
+    table.insert(coltypes, col.type or col[2])
+  end
+  local stmt = thismod.conn:prepare(thismod.prepare_insert_sql(tablename, colnames))
+  return stmt, stmt:bind_params(coltypes)
+end
+
+---- UPDATE prepare
+
+function thismod.prepare_update_sql(tablename, colnames, where)
+  return 'UPDATE ' .. tablename .. ' SET ' .. table.concat(colnames, ',') .. ' WHERE ' .. where
+end
+function thismod.prepare_update(tablename, cols, where, wheretypes)
+  local colnames, paramtypes = {}, {}
+  for _, col in ipairs(cols) do
+    table.insert(colnames, (col.name or col[1]) .. '=?')
+    table.insert(paramtypes, col.type or col[2])
+  end
+  for _, wheretype in ipairs(wheretypes) do
+    table.insert(paramtypes, wheretype)
+  end
+  local stmt = thismod.conn:prepare(thismod.prepare_update_sql(tablename, colnames, where))
+  return stmt, stmt:bind_params(paramtypes)
+end
+
+---- DELETE prepare
+
+function thismod.prepare_delete(tablename, where, wheretypes)
+  local stmt = thismod.conn:prepare('DELETE FROM ' .. tablename .. ' WHERE ' .. where)
+  return stmt, stmt:bind_params(wheretypes)
+end
+
+---- SELECT prepare
+
+function thismod.prepare_select_sql(tablename, colnames, where)
+  return 'SELECT ' .. table.concat(colnames, ',') .. ' FROM ' .. tablename .. ' WHERE ' .. where
+end
+function thismod.prepare_select(tablename, cols, where, wheretypes)
+  local colnames, coltypes = {}, {}
+  for _, col in ipairs(cols) do
+    table.insert(colnames, col.name or col[1])
+    table.insert(coltypes, col.type or col[2])
+  end
+  local stmt = thismod.conn:prepare(thismod.prepare_select_sql(tablename, colnames, where))
+  return stmt, stmt:bind_params(wheretypes), stmt:bind_result(coltypes)
+end