MySQL
As with sqlite section, here we introduce libmysqlclient interface directly.
Data models are introduced here.
Note: After executing a query with
mysql_real_querylike functions, if there are returning results, we must consume the result, otherwise we will get following error when we execute next query.
Commands out of sync; you can't run this command now
//! MySQL 8.0 API demo
//! https://dev.mysql.com/doc/c-api/8.0/en/c-api-basic-interface-usage.html
//!
const std = @import("std");
const Allocator = std.mem.Allocator;
const c = @cImport({
@cInclude("mysql.h");
});
const print = std.debug.print;
pub const DBInfo = struct {
host: [:0]const u8,
user: [:0]const u8,
password: [:0]const u8,
database: [:0]const u8,
port: u32 = 3306,
};
pub const DB = struct {
conn: *c.MYSQL,
allocator: Allocator,
fn init(allocator: Allocator, db_info: DBInfo) !DB {
const db = c.mysql_init(null);
if (db == null) {
return error.initError;
}
if (c.mysql_real_connect(
db,
db_info.host,
db_info.user,
db_info.password,
db_info.database,
db_info.port,
null,
c.CLIENT_MULTI_STATEMENTS,
) == null) {
print("Connect to database failed: {s}\n", .{c.mysql_error(db)});
return error.connectError;
}
return .{
.conn = db,
.allocator = allocator,
};
}
fn deinit(self: DB) void {
c.mysql_close(self.conn);
}
fn execute(self: DB, query: []const u8) !void {
if (c.mysql_real_query(self.conn, query.ptr, query.len) != 0) {
print("Exec query failed: {s}\n", .{c.mysql_error(self.conn)});
return error.execError;
}
}
fn queryTable(self: DB) !void {
const query =
\\ SELECT
\\ c.name,
\\ cc.name
\\ FROM
\\ cats c
\\ INNER JOIN cat_colors cc ON cc.id = c.color_id;
\\
;
try self.execute(query);
const result = c.mysql_store_result(self.conn);
if (result == null) {
print("Store result failed: {s}\n", .{c.mysql_error(self.conn)});
return error.storeResultError;
}
defer c.mysql_free_result(result);
while (c.mysql_fetch_row(result)) |row| {
const cat_name = row[0];
const color_name = row[1];
print("Cat: {s}, Color: {s}\n", .{ cat_name, color_name });
}
}
fn insertTable(self: DB) !void {
const cat_colors = .{
.{
"Blue",
.{ "Tigger", "Sammy" },
},
.{
"Black",
.{ "Oreo", "Biscuit" },
},
};
const insert_color_stmt: *c.MYSQL_STMT = blk: {
const stmt = c.mysql_stmt_init(self.conn);
if (stmt == null) {
return error.initStmt;
}
errdefer _ = c.mysql_stmt_close(stmt);
const insert_color_query = "INSERT INTO cat_colors (name) values (?)";
if (c.mysql_stmt_prepare(stmt, insert_color_query, insert_color_query.len) != 0) {
print("Prepare color stmt failed, msg:{s}\n", .{c.mysql_error(self.conn)});
return error.prepareStmt;
}
break :blk stmt.?;
};
defer _ = c.mysql_stmt_close(insert_color_stmt);
const insert_cat_stmt = blk: {
const stmt = c.mysql_stmt_init(self.conn);
if (stmt == null) {
return error.initStmt;
}
errdefer _ = c.mysql_stmt_close(stmt);
const insert_cat_query = "INSERT INTO cats (name, color_id) values (?, ?)";
if (c.mysql_stmt_prepare(stmt, insert_cat_query, insert_cat_query.len) != 0) {
print("Prepare cat stmt failed: {s}\n", .{c.mysql_error(self.conn)});
return error.prepareStmt;
}
break :blk stmt.?;
};
defer _ = c.mysql_stmt_close(insert_cat_stmt);
inline for (cat_colors) |row| {
const color = row.@"0";
const cat_names = row.@"1";
var color_binds = [_]c.MYSQL_BIND{std.mem.zeroes(c.MYSQL_BIND)};
color_binds[0].buffer_type = c.MYSQL_TYPE_STRING;
color_binds[0].buffer_length = color.len;
color_binds[0].is_null = 0;
color_binds[0].buffer = @constCast(@ptrCast(color.ptr));
if (c.mysql_stmt_bind_param(insert_color_stmt, &color_binds)) {
print("Bind color param failed: {s}\n", .{c.mysql_error(self.conn)});
return error.bindParamError;
}
if (c.mysql_stmt_execute(insert_color_stmt) != 0) {
print("Exec color stmt failed: {s}\n", .{c.mysql_error(self.conn)});
return error.execStmtError;
}
const last_id = c.mysql_stmt_insert_id(insert_color_stmt);
_ = c.mysql_stmt_reset(insert_color_stmt);
inline for (cat_names) |cat_name| {
var cat_binds = [_]c.MYSQL_BIND{ std.mem.zeroes(c.MYSQL_BIND), std.mem.zeroes(c.MYSQL_BIND) };
cat_binds[0].buffer_type = c.MYSQL_TYPE_STRING;
cat_binds[0].buffer_length = cat_name.len;
cat_binds[0].buffer = @constCast(@ptrCast(cat_name.ptr));
cat_binds[1].buffer_type = c.MYSQL_TYPE_LONG;
cat_binds[1].length = (@as(c_ulong, 1));
cat_binds[1].buffer = @constCast(@ptrCast(&last_id));
if (c.mysql_stmt_bind_param(insert_cat_stmt, &cat_binds)) {
print("Bind cat param failed: {s}\n", .{c.mysql_error(self.conn)});
return error.bindParamError;
}
if (c.mysql_stmt_execute(insert_cat_stmt) != 0) {
print("Exec cat stmt failed: {s}\n", .{c.mysql_error(self.conn)});
return error.execStmtError;
}
_ = c.mysql_stmt_reset(insert_cat_stmt);
}
}
}
};
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
const allocator = gpa.allocator();
const version = c.mysql_get_client_version();
print("MySQL client version is {}\n", .{version});
const db = try DB.init(allocator, .{
.database = "public",
.host = "127.0.0.1",
.user = "root",
.password = "password",
});
defer db.deinit();
try db.execute(
\\ CREATE TABLE IF NOT EXISTS cat_colors (
\\ id INT AUTO_INCREMENT PRIMARY KEY,
\\ name VARCHAR(255) NOT NULL
\\);
\\
\\CREATE TABLE IF NOT EXISTS cats (
\\ id INT AUTO_INCREMENT PRIMARY KEY,
\\ name VARCHAR(255) NOT NULL,
\\ color_id INT NOT NULL
\\)
);
// Since we use multi-statement, we need to consume all results.
// Otherwise we will get following error when we execute next query.
// Commands out of sync; you can't run this command now
//
// https://dev.mysql.com/doc/c-api/8.0/en/mysql-next-result.html
while (c.mysql_next_result(db.conn) == 0) {
const res = c.mysql_store_result(db.conn);
c.mysql_free_result(res);
}
try db.insertTable();
try db.queryTable();
}