英文原文鏈接：https://cstack.github.io/db_tutorial/parts/part9.html
上次我們注意到我們仍然按照未排序的順序存儲key。我們將解決該問題，並增加對重複key的檢查。
當前，我們的execute_insert函數總是選擇在表尾插入。但是我們應該先檢索到合適的位置，然後再插入。如果key已經存在，則返回error。
ExecuteResult execute_insert(Statement* statement, Table* table) {
void* node = get_page(table->pager, table->root_page_num);
- if ((*leaf_node_num_cells(node) >= LEAF_NODE_MAX_CELLS)) {
+ uint32_t num_cells = (*leaf_node_num_cells(node));
+ if (num_cells >= LEAF_NODE_MAX_CELLS) {
return EXECUTE_TABLE_FULL;
}
Row* row_to_insert = &(statement->row_to_insert);
- Cursor* cursor = table_end(table);
+ uint32_t key_to_insert = row_to_insert->id;
+ Cursor* cursor = table_find(table, key_to_insert);
+
+ if (cursor->cell_num < num_cells) {
+ uint32_t key_at_index = *leaf_node_key(node, cursor->cell_num);
+ if (key_at_index == key_to_insert) {
+ return EXECUTE_DUPLICATE_KEY;
+ }
+ }
leaf_node_insert(cursor, row_to_insert->id, row_to_insert);
自此，我們不再需要table_end函數了。取而代之是定義一個函數實現，通過一個給定的key檢索樹。
+/*
+Return the position of the given key.
+If the key is not present, return the position
+where it should be inserted
+*/
+Cursor* table_find(Table* table, uint32_t key) {
+ uint32_t root_page_num = table->root_page_num;
+ void* root_node = get_page(table->pager, root_page_num);
+
+ if (get_node_type(root_node) == NODE_LEAF) {
+ return leaf_node_find(table, root_page_num, key);
+ } else {
+ printf("Need to implement searching an internal node\n");
+ exit(EXIT_FAILURE);
+ }
+}
我們先不管內部節點的事情，因爲目前我們還沒有實現內部節點。我們剋使用二分查找來檢索葉子節點。
+/*葉子節點是順序存儲的*/
+Cursor* leaf_node_find(Table* table, uint32_t page_num, uint32_t key) {
+ void* node = get_page(table->pager, page_num);
+ uint32_t num_cells = *leaf_node_num_cells(node);
+
+ Cursor* cursor = malloc(sizeof(Cursor));
+ cursor->table = table;
+ cursor->page_num = page_num;
+
+ // Binary search
+ uint32_t min_index = 0;
+ uint32_t one_past_max_index = num_cells;
+ while (one_past_max_index != min_index) {
+ uint32_t index = (min_index + one_past_max_index) / 2;
+ uint32_t key_at_index = *leaf_node_key(node, index);
+ if (key == key_at_index) {
+ cursor->cell_num = index;
+ return cursor;
+ }
+ if (key < key_at_index) {
+ one_past_max_index = index;
+ } else {
+ min_index = index + 1;
+ }
+ }
+
+ cursor->cell_num = min_index;
+ return cursor;
+}
這個返回返回值：
- key的位置；
- 或者另外一個key的位置，這種情況下，我們需要進行move以便於存儲當前值；
- 或者最後的位置。
手工做下測試，可以看到2點變化：
1、key不允許重複
2、插入的數據會自動進行排序。
db > insert 1 user1 [email protected]
Executed.
db > insert 1 user1 [email protected]
Error: Duplicate key.
Error: Table full.
db > insert 3 user3 [email protected]
Executed.
db > insert 2 user2 [email protected]
Executed.
db > select
(1, user1, [email protected])
(2, user2, [email protected])
(3, user3, [email protected])
Executed.
至此最新的代碼如下：
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* 定義 元數據操作結果*/
enum MetaCommandResult_t {
META_COMMAND_SUCCESS,
META_COMMAND_UNRECOGNIZED_COMMAND
};
typedef enum MetaCommandResult_t MetaCommandResult;
/* 執行結果*/
enum ExecuteResult_t {
EXECUTE_SUCCESS,
EXECUTE_DUPLICATE_KEY,
EXECUTE_TABLE_FULL
};
typedef enum ExecuteResult_t ExecuteResult;
/* sql解析結果 */
enum PrepareResult_t {
PREPARE_SUCCESS,
PREPARE_NEGATIVE_ID,
PREPARE_STRING_TOO_LONG,
PREPARE_SYNTAX_ERROR,
PREPARE_UNRECOGNIZED_STATEMENT
};
typedef enum PrepareResult_t PrepareResult;
/**
* 行定義，對應具體的業務
*/
const uint32_t COLUMN_USERNAME_SIZE = 32;
const uint32_t COLUMN_EMAIL_SIZE = 255;
struct Row_t {
uint32_t id;
char username[COLUMN_USERNAME_SIZE + 1];
char email[COLUMN_EMAIL_SIZE + 1];
};
typedef struct Row_t Row;
/* sql type*/
enum StatementType_t {
STATEMENT_INSERT,
STATEMENT_SELECT
};
typedef enum StatementType_t StatementType;
struct Statement_t {
StatementType type;
Row row_to_insert; /* only used by insert statement */
};
typedef struct Statement_t Statement;
#define size_of_attribute(Struct, Attribute) sizeof(((Struct*)0)->Attribute)
const uint32_t ID_SIZE = size_of_attribute(Row, id);
const uint32_t USERNAME_SIZE = size_of_attribute(Row, username);
const uint32_t EMAIL_SIZE = size_of_attribute(Row, email);
const uint32_t ID_OFFSET = 0;
const uint32_t USERNAME_OFFSET = ID_OFFSET + ID_SIZE;
const uint32_t EMAIL_OFFSET = USERNAME_OFFSET + USERNAME_SIZE;
const uint32_t ROW_SIZE = ID_SIZE + USERNAME_SIZE + EMAIL_SIZE;
/* 大部分系統結構的頁大小都是4K ，所以這裏也定義爲4K 這樣就不用做轉換 */
const uint32_t PAGE_SIZE = 4096;
const uint32_t TABLE_MAX_PAGES = 100;
/**
* 頁和表定義
*/
struct Pager_t {
int file_descriptor;
uint32_t file_length;
uint32_t num_pages;
void *pages[TABLE_MAX_PAGES];
};
typedef struct Pager_t Pager;
struct Table_t {
Pager *pager; //Pager管理器
uint32_t root_page_num; //根節點page編號
};
typedef struct Table_t Table;
/**
* Cursor定義
*/
struct Cursor_t {
Table *table;
uint32_t page_num;
uint32_t cell_num;
bool end_of_table; // Indicates a position one past the last element
};
typedef struct Cursor_t Cursor;
enum NodeType_t {
NODE_INTERNAL, NODE_LEAF
};
typedef enum NodeType_t NodeType;
/**
* Common Node Header Layout
*/
const uint32_t NODE_TYPE_SIZE = sizeof(uint8_t);
const uint32_t NODE_TYPE_OFFSET = 0;
const uint32_t IS_ROOT_SIZE = sizeof(uint8_t);
const uint32_t IS_ROOT_OFFSET = NODE_TYPE_SIZE;
const uint32_t PARENT_POINTER_SIZE = sizeof(uint32_t);
const uint32_t PARENT_POINTER_OFFSET = IS_ROOT_OFFSET + IS_ROOT_SIZE;
const uint8_t COMMON_NODE_HEADER_SIZE =
NODE_TYPE_SIZE + IS_ROOT_SIZE + PARENT_POINTER_SIZE;
/**
* Leaf Node Header Layout
*/
const uint32_t LEAF_NODE_NUM_CELLS_SIZE = sizeof(uint32_t);
const uint32_t LEAF_NODE_NUM_CELLS_OFFSET = COMMON_NODE_HEADER_SIZE;
const uint32_t LEAF_NODE_HEADER_SIZE =
COMMON_NODE_HEADER_SIZE + LEAF_NODE_NUM_CELLS_SIZE;
/**
* Leaf Node Body Layout
*/
const uint32_t LEAF_NODE_KEY_SIZE = sizeof(uint32_t);
const uint32_t LEAF_NODE_KEY_OFFSET = 0;
const uint32_t LEAF_NODE_VALUE_SIZE = ROW_SIZE;
const uint32_t LEAF_NODE_VALUE_OFFSET =
LEAF_NODE_KEY_OFFSET + LEAF_NODE_KEY_SIZE;
const uint32_t LEAF_NODE_CELL_SIZE = LEAF_NODE_KEY_SIZE + LEAF_NODE_VALUE_SIZE;
const uint32_t LEAF_NODE_SPACE_FOR_CELLS = PAGE_SIZE - LEAF_NODE_HEADER_SIZE;
const uint32_t LEAF_NODE_MAX_CELLS =
LEAF_NODE_SPACE_FOR_CELLS / LEAF_NODE_CELL_SIZE;
/**
* 獲取頁num對應的頁
* @param table
* @param row_num
* @return
*/
void *get_page(Pager *pager, uint32_t page_num) {
if (page_num > TABLE_MAX_PAGES) {
printf("Tried to fetch page number out of bounds. %d > %d\n", page_num,
TABLE_MAX_PAGES);
exit(EXIT_FAILURE);
}
if (pager->pages[page_num] == NULL) {
// Cache miss. Allocate memory and load from file.
void *page = malloc(PAGE_SIZE);
uint32_t num_pages = pager->file_length / PAGE_SIZE;
// We might save a partial page at the end of the file
if (pager->file_length % PAGE_SIZE) {
num_pages += 1;
}
if (page_num <= num_pages) {
lseek(pager->file_descriptor, page_num * PAGE_SIZE, SEEK_SET);
ssize_t bytes_read = read(pager->file_descriptor, page, PAGE_SIZE);
if (bytes_read == -1) {
printf("Error reading file: %d\n", errno);
exit(EXIT_FAILURE);
}
}
pager->pages[page_num] = page;
if (page_num >= pager->num_pages) {
pager->num_pages = page_num + 1;
}
}
return pager->pages[page_num];
}
/**
* 打開pager
* @param filename
* @return
*/
Pager *pager_open(const char *filename) {
int fd = open(filename,
O_RDWR | // Read/Write mode
O_CREAT, // Create file if it does not exist
S_IWUSR | // User write permission
S_IRUSR // User read permission
);
if (fd == -1) {
printf("Unable to open file\n");
exit(EXIT_FAILURE);
}
off_t file_length = lseek(fd, 0, SEEK_END);
Pager *pager = malloc(sizeof(Pager));
pager->file_descriptor = fd;
pager->file_length = file_length;
pager->num_pages = (file_length / PAGE_SIZE);
if (file_length % PAGE_SIZE != 0) {
printf("Db file is not a whole number of pages. Corrupt file.\n");
exit(EXIT_FAILURE);
}
for (uint32_t i = 0; i < TABLE_MAX_PAGES; i++) {
pager->pages[i] = NULL;
}
return pager;
}
/* 獲取cell個數*/
uint32_t *leaf_node_num_cells(void *node) {
return (char *) node + LEAF_NODE_NUM_CELLS_OFFSET;
}
/* 根據cell編碼獲取相應的cell*/
void *leaf_node_cell(void *node, uint32_t cell_num) {
return (char *) node + LEAF_NODE_HEADER_SIZE + cell_num * LEAF_NODE_CELL_SIZE;
}
/* 根據cell編碼獲取key*/
uint32_t *leaf_node_key(void *node, uint32_t cell_num) {
return leaf_node_cell(node, cell_num);
}
/* 根據cell編碼獲取value*/
void *leaf_node_value(void *node, uint32_t cell_num) {
return leaf_node_cell(node, cell_num) + LEAF_NODE_KEY_SIZE;
}
/**
* 通過key得到合理的cursor
* @param table
* @param page_num
* @param key
* @return
*/
Cursor* leaf_node_find(Table* table, uint32_t page_num, uint32_t key) {
void* node = get_page(table->pager, page_num);
uint32_t num_cells = *leaf_node_num_cells(node);
Cursor* cursor = malloc(sizeof(Cursor));
cursor->table = table;
cursor->page_num = page_num;
// Binary search
uint32_t min_index = 0;
uint32_t one_past_max_index = num_cells;
while (one_past_max_index != min_index) {
uint32_t index = (min_index + one_past_max_index) / 2;
uint32_t key_at_index = *leaf_node_key(node, index);
if (key == key_at_index) {
cursor->cell_num = index;
return cursor;
}
if (key < key_at_index) {
one_past_max_index = index;
} else {
min_index = index + 1;
}
}
cursor->cell_num = min_index;
return cursor;
}
/**
* node type set/get function
* @param node
* @return
*/
NodeType get_node_type(void* node) {
uint8_t value = *((uint8_t*)(node + NODE_TYPE_OFFSET));
return (NodeType)value;
}
void set_node_type(void* node, NodeType type) {
uint8_t value = type;
*((uint8_t*)(node + NODE_TYPE_OFFSET)) = value;
}
/**
* Return the position of the given key.
* If the key is not present, return the position
* where it should be inserted
*/
Cursor* table_find(Table* table, uint32_t key) {
uint32_t root_page_num = table->root_page_num;
void* root_node = get_page(table->pager, root_page_num);
if (get_node_type(root_node) == NODE_LEAF) {
return leaf_node_find(table, root_page_num, key);
} else {
printf("Need to implement searching an internal node\n");
exit(EXIT_FAILURE);
}
}
/* 初始化葉子節點 */
void initialize_leaf_node(void *node) {
set_node_type(node, NODE_LEAF);
*leaf_node_num_cells(node) = 0;
}
/**
* 打印系統參數
*/
void print_constants() {
printf("ROW_SIZE: %d\n", ROW_SIZE);
printf("COMMON_NODE_HEADER_SIZE: %d\n", COMMON_NODE_HEADER_SIZE);
printf("LEAF_NODE_HEADER_SIZE: %d\n", LEAF_NODE_HEADER_SIZE);
printf("LEAF_NODE_CELL_SIZE: %d\n", LEAF_NODE_CELL_SIZE);
printf("LEAF_NODE_SPACE_FOR_CELLS: %d\n", LEAF_NODE_SPACE_FOR_CELLS);
printf("LEAF_NODE_MAX_CELLS: %d\n", LEAF_NODE_MAX_CELLS);
}
/**
* 葉子節點可視化
*/
void print_leaf_node(void *node) {
uint32_t num_cells = *leaf_node_num_cells(node);
printf("leaf (size %d)\n", num_cells);
for (uint32_t i = 0; i < num_cells; i++) {
uint32_t key = *leaf_node_key(node, i);
printf(" - %d : %d\n", i, key);
}
}
/**
* 序列化： 將row寫到內存中
*/
void serialize_row(Row *source, void *destination) {
memcpy(destination + ID_OFFSET, &(source->id), ID_SIZE);
memcpy(destination + USERNAME_OFFSET, &(source->username), USERNAME_SIZE);
memcpy(destination + EMAIL_OFFSET, &(source->email), EMAIL_SIZE);
}
/* 反序列化 */
void deserialize_row(void *source, Row *destination) {
memcpy(&(destination->id), source + ID_OFFSET, ID_SIZE);
memcpy(&(destination->username), source + USERNAME_OFFSET, USERNAME_SIZE);
memcpy(&(destination->email), source + EMAIL_OFFSET, EMAIL_SIZE);
}
/**
* Cursor api
* @param row
*/
Cursor *table_start(Table *table) {
Cursor *cursor = malloc(sizeof(Cursor));
cursor->table = table;
cursor->page_num = table->root_page_num;
cursor->cell_num = 0;
void *root_node = get_page(table->pager, table->root_page_num);
uint32_t num_cells = *leaf_node_num_cells(root_node);
cursor->end_of_table = (num_cells == 0);
return cursor;
}
/**
* 計算插入位置， 行插入槽
*/
void *cursor_value(Cursor *cursor) {
uint32_t page_num = cursor->page_num;
void *page = get_page(cursor->table->pager, page_num);
return leaf_node_value(page, cursor->cell_num);
}
/**
* rownum 加1
* @param cursor
*/
void cursor_advance(Cursor *cursor) {
uint32_t page_num = cursor->page_num;
void *node = get_page(cursor->table->pager, page_num);
cursor->cell_num += 1;
if (cursor->cell_num >= (*leaf_node_num_cells(node))) {
cursor->end_of_table = true;
}
}
void print_row(Row *row) {
printf("(%d, %s, %s)\n", row->id, row->username, row->email);
}
/**
* 打開數據庫文件並建立連接
* @param filename
* @return
*/
Table *db_open(const char *filename) {
Pager *pager = pager_open(filename);
Table *table = malloc(sizeof(Table));
table->pager = pager;
table->root_page_num = 0;
if (pager->num_pages == 0) {
// New database file. Initialize page 0 as leaf node.
void *root_node = get_page(pager, 0);
initialize_leaf_node(root_node);
}
return table;
}
/* 接收輸入*/
struct InputBuffer_t {
char *buffer;
size_t buffer_length;
ssize_t input_length;
};
typedef struct InputBuffer_t InputBuffer;
/* 初始化buffer */
InputBuffer *new_input_buffer() {
InputBuffer *input_buffer = malloc(sizeof(InputBuffer));
input_buffer->buffer = NULL;
input_buffer->buffer_length = 0;
input_buffer->input_length = 0;
return input_buffer;
}
void print_prompt() { printf("db > "); }
/**
* 按行從標準輸入讀取
*/
void read_input(InputBuffer *input_buffer) {
ssize_t bytes_read =
getline(&(input_buffer->buffer), &(input_buffer->buffer_length), stdin);
if (bytes_read <= 0) {
printf("Error reading input\n");
exit(EXIT_FAILURE);
}
// Ignore trailing newline
input_buffer->input_length = bytes_read - 1;
input_buffer->buffer[bytes_read - 1] = 0;
}
/**
* 刷新頁到文件（指定頁號）
* @param pager
* @param page_num
* @param size
*/
void pager_flush(Pager *pager, uint32_t page_num) {
if (pager->pages[page_num] == NULL) {
printf("Tried to flush null page\n");
exit(EXIT_FAILURE);
}
off_t offset = lseek(pager->file_descriptor, page_num * PAGE_SIZE, SEEK_SET);
if (offset == -1) {
printf("Error seeking: %d\n", errno);
exit(EXIT_FAILURE);
}
ssize_t bytes_written =
write(pager->file_descriptor, pager->pages[page_num], PAGE_SIZE);
if (bytes_written == -1) {
printf("Error writing: %d\n", errno);
exit(EXIT_FAILURE);
}
}
/**
* 關閉數據連接
*/
void db_close(Table *table) {
Pager *pager = table->pager;
for (uint32_t i = 0; i < pager->num_pages; i++) {
if (pager->pages[i] == NULL) {
continue;
}
pager_flush(pager, i);
free(pager->pages[i]);
pager->pages[i] = NULL;
}
int result = close(pager->file_descriptor);
if (result == -1) {
printf("Error closing db file.\n");
exit(EXIT_FAILURE);
}
for (uint32_t i = 0; i < TABLE_MAX_PAGES; i++) {
void *page = pager->pages[i];
if (page) {
free(page);
pager->pages[i] = NULL;
}
}
free(pager);
}
/**
* 元數據命令處理
*/
MetaCommandResult do_meta_command(InputBuffer *input_buffer, Table *table) {
if (strcmp(input_buffer->buffer, ".exit") == 0) {
db_close(table);
exit(EXIT_SUCCESS);
} else if (strcmp(input_buffer->buffer, ".btree") == 0) {
printf("Tree:\n");
print_leaf_node(get_page(table->pager, 0));
return META_COMMAND_SUCCESS;
} else if (strcmp(input_buffer->buffer, ".constants") == 0) {
printf("Constants:\n");
print_constants();
return META_COMMAND_SUCCESS;
} else {
return META_COMMAND_UNRECOGNIZED_COMMAND;
}
}
/**
* insert解析和校驗
*/
PrepareResult prepare_insert(InputBuffer *input_buffer, Statement *statement) {
statement->type = STATEMENT_INSERT;
char *keyword = strtok(input_buffer->buffer, " ");
char *id_string = strtok(NULL, " ");
char *username = strtok(NULL, " ");
char *email = strtok(NULL, " ");
if (id_string == NULL || username == NULL || email == NULL) {
return PREPARE_SYNTAX_ERROR;
}
int id = atoi(id_string);
if (id < 0) {
return PREPARE_NEGATIVE_ID;
}
if (strlen(username) > COLUMN_USERNAME_SIZE) {
return PREPARE_STRING_TOO_LONG;
}
if (strlen(email) > COLUMN_EMAIL_SIZE) {
return PREPARE_STRING_TOO_LONG;
}
statement->row_to_insert.id = id;
strcpy(statement->row_to_insert.username, username);
strcpy(statement->row_to_insert.email, email);
return PREPARE_SUCCESS;
}
/**
* sql解析
*/
PrepareResult prepare_statement(InputBuffer *input_buffer, Statement *statement) {
if (strncasecmp(input_buffer->buffer, "insert", 6) == 0) {
return prepare_insert(input_buffer, statement);
}
if (strncasecmp(input_buffer->buffer, "select", 6) == 0) {
statement->type = STATEMENT_SELECT;
return PREPARE_SUCCESS;
}
return PREPARE_UNRECOGNIZED_STATEMENT;
}
/**
* 向葉子節點插入數據
*/
void leaf_node_insert(Cursor *cursor, uint32_t key, Row *value) {
void *node = get_page(cursor->table->pager, cursor->page_num);
uint32_t num_cells = *leaf_node_num_cells(node);
if (num_cells >= LEAF_NODE_MAX_CELLS) {
// Node full
printf("Need to implement splitting a leaf node.\n");
exit(EXIT_FAILURE);
}
if (cursor->cell_num < num_cells) {
// Make room for new cell 會有多個嗎？有必要循環嗎？TODO
for (uint32_t i = num_cells; i > cursor->cell_num; i--) {
memcpy(leaf_node_cell(node, i), leaf_node_cell(node, i - 1),
LEAF_NODE_CELL_SIZE);
}
}
/* 寫入數據 */
*(leaf_node_num_cells(node)) += 1;
*(leaf_node_key(node, cursor->cell_num)) = key;
serialize_row(value, leaf_node_value(node, cursor->cell_num));
}
/**
* 執行insert
*/
ExecuteResult execute_insert(Statement *statement, Table *table) {
void *node = get_page(table->pager, table->root_page_num);
uint32_t num_cells = (*leaf_node_num_cells(node));
if (num_cells >= LEAF_NODE_MAX_CELLS) {
return EXECUTE_TABLE_FULL;
}
Row *row_to_insert = &(statement->row_to_insert);
uint32_t key_to_insert = row_to_insert->id;
Cursor* cursor = table_find(table, key_to_insert);
if (cursor->cell_num < num_cells) {
uint32_t key_at_index = *leaf_node_key(node, cursor->cell_num);
if (key_at_index == key_to_insert) {
return EXECUTE_DUPLICATE_KEY;
}
}
leaf_node_insert(cursor, row_to_insert->id, row_to_insert);
free(cursor);
return EXECUTE_SUCCESS;
}
/* 執行查詢*/
ExecuteResult execute_select(Statement *statement, Table *table) {
Row row;
Cursor *cursor = table_start(table);
while (!(cursor->end_of_table)) {
deserialize_row(cursor_value(cursor), &row);
print_row(&row);
cursor_advance(cursor);
}
free(cursor);
return EXECUTE_SUCCESS;
}
/* sql執行*/
ExecuteResult execute_statement(Statement *statement, Table *table) {
switch (statement->type) {
case (STATEMENT_INSERT):
return execute_insert(statement, table);
case (STATEMENT_SELECT):
return execute_select(statement, table);
}
}
/* 主函數*/
int main(int argc, char *argv[]) {
if (argc < 2) {
printf("Must supply a database filename.\n");
exit(EXIT_FAILURE);
}
char *filename = argv[1];
Table *table = db_open(filename);
InputBuffer *input_buffer = new_input_buffer();
while (true) {
print_prompt();
read_input(input_buffer);
if (input_buffer->buffer[0] == '.') {
switch (do_meta_command(input_buffer, table)) {
case (META_COMMAND_SUCCESS):
continue;
case (META_COMMAND_UNRECOGNIZED_COMMAND):
printf("Unrecognized command '%s'\n", input_buffer->buffer);
continue;
}
}
Statement statement;
switch (prepare_statement(input_buffer, &statement)) {
case (PREPARE_SUCCESS):
break;
case (PREPARE_NEGATIVE_ID):
printf("ID must be positive.\n");
continue;
case (PREPARE_STRING_TOO_LONG):
printf("String is too long.\n");
continue;
case (PREPARE_SYNTAX_ERROR):
printf("Syntax error. Could not parse statement.\n");
continue;
case (PREPARE_UNRECOGNIZED_STATEMENT):
printf("Unrecognized keyword at start of '%s'.\n",
input_buffer->buffer);
continue;
}
switch (execute_statement(&statement, table)) {
case (EXECUTE_SUCCESS):
printf("Executed.\n");
break;
case (EXECUTE_DUPLICATE_KEY):
printf("Error: Duplicate key.\n");
case (EXECUTE_TABLE_FULL):
printf("Error: Table full.\n");
break;
}
}
}