diff --git a/src/core/query-builder.ts b/src/core/query-builder.ts
index 3b1e70c..af7bc6d 100644
--- a/src/core/query-builder.ts
+++ b/src/core/query-builder.ts
@@ -31,23 +31,9 @@ export function buildSelectQuery(table: string, options: TableQueryOptions): { s
   const whereClauses: string[] = [];
   const params: any[] = [];
 
-  // Column filters
-  for (const filter of filters) {
-    if (filter.value) {
-      whereClauses.push(`${escapeIdentifier(filter.column)} LIKE ?`);
-      params.push(`%${filter.value}%`);
-    }
-  }
-
-  // Global filter
-  if (globalFilter) {
-    const globalConditions = columns.map(col => `${escapeIdentifier(col)} LIKE ?`).join(' OR ');
-    whereClauses.push(`(${globalConditions})`);
-    // Add param for each column in the OR clause
-    for (let i = 0; i < columns.length; i++) {
-      params.push(`%${globalFilter}%`);
-    }
-  }
+  const { conditions, params: filterParams } = buildFilterConditions(filters, globalFilter, columns);
+  whereClauses.push(...conditions);
+  params.push(...filterParams);
 
   if (whereClauses.length > 0) {
     sql += ` WHERE ${whereClauses.join(' AND ')}`;
@@ -79,26 +65,47 @@ export function buildCountQuery(table: string, options: TableCountOptions): { sq
   const whereClauses: string[] = [];
   const params: any[] = [];
 
+  const { conditions, params: filterParams } = buildFilterConditions(filters, globalFilter, columns);
+  whereClauses.push(...conditions);
+  params.push(...filterParams);
+
+  if (whereClauses.length > 0) {
+    sql += ` WHERE ${whereClauses.join(' AND ')}`;
+  }
+
+  return { sql, params };
+}
+
+/**
+ * Helper to build WHERE conditions for column filters and global search.
+ */
+function buildFilterConditions(
+  filters: { column: string; value: string }[] = [],
+  globalFilter: string | undefined,
+  searchColumns: string[]
+): { conditions: string[]; params: any[] } {
+  const conditions: string[] = [];
+  const params: any[] = [];
+
   // Column filters
   for (const filter of filters) {
     if (filter.value) {
-      whereClauses.push(`${escapeIdentifier(filter.column)} LIKE ?`);
+      conditions.push(`${escapeIdentifier(filter.column)} LIKE ?`);
       params.push(`%${filter.value}%`);
     }
   }
 
   // Global filter
-  if (globalFilter && columns.length > 0) {
-    const globalConditions = columns.map(col => `${escapeIdentifier(col)} LIKE ?`).join(' OR ');
-    whereClauses.push(`(${globalConditions})`);
-    for (let i = 0; i < columns.length; i++) {
+  if (globalFilter && searchColumns.length > 0) {
+    const globalConditions = searchColumns
+      .map(col => `${escapeIdentifier(col)} LIKE ?`)
+      .join(' OR ');
+
+    conditions.push(`(${globalConditions})`);
+    for (let i = 0; i < searchColumns.length; i++) {
       params.push(`%${globalFilter}%`);
     }
   }
 
-  if (whereClauses.length > 0) {
-    sql += ` WHERE ${whereClauses.join(' AND ')}`;
-  }
-
-  return { sql, params };
+  return { conditions, params };
 }
diff --git a/tests/unit/query-builder.test.ts b/tests/unit/query-builder.test.ts
index 5c9ab12..9acd43e 100644
--- a/tests/unit/query-builder.test.ts
+++ b/tests/unit/query-builder.test.ts
@@ -34,5 +34,64 @@ describe('Query Builder', () => {
       const { sql } = buildSelectQuery('logs', options);
       assert.strictEqual(sql, 'SELECT * FROM "logs" ORDER BY "created_at" DESC LIMIT 10 OFFSET 20');
     });
+
+    it('should handle global filter with explicit columns', () => {
+      const options = {
+        columns: ['name', 'description'],
+        globalFilter: 'test'
+      };
+      const { sql, params } = buildSelectQuery('products', options);
+      assert.strictEqual(sql, 'SELECT "name", "description" FROM "products" WHERE ("name" LIKE ? OR "description" LIKE ?)');
+      assert.deepStrictEqual(params, ['%test%', '%test%']);
+    });
+
+    it('should handle global filter with default columns (edge case)', () => {
+      // This documents current behavior where default ['*'] results in " * " LIKE ?
+      const options = {
+        globalFilter: 'test'
+      };
+      const { sql, params } = buildSelectQuery('products', options);
+      assert.strictEqual(sql, 'SELECT * FROM "products" WHERE ("*" LIKE ?)');
+      assert.deepStrictEqual(params, ['%test%']);
+    });
+
+    it('should handle global filter with empty columns (safe behavior)', () => {
+      const options = {
+        columns: [],
+        globalFilter: 'test'
+      };
+      const { sql, params } = buildSelectQuery('products', options);
+      // Implementation should avoid generating WHERE ()
+      assert.strictEqual(sql, 'SELECT  FROM "products"');
+      assert.deepStrictEqual(params, []);
+    });
+  });
+
+  describe('buildCountQuery', () => {
+    it('should build simple count', () => {
+      const { sql, params } = buildCountQuery('my_table', {});
+      assert.strictEqual(sql, 'SELECT COUNT(*) as count FROM "my_table"');
+      assert.deepStrictEqual(params, []);
+    });
+
+    it('should handle global filter with explicit columns', () => {
+      const options = {
+        columns: ['name', 'description'],
+        globalFilter: 'test'
+      };
+      const { sql, params } = buildCountQuery('products', options);
+      assert.strictEqual(sql, 'SELECT COUNT(*) as count FROM "products" WHERE ("name" LIKE ? OR "description" LIKE ?)');
+      assert.deepStrictEqual(params, ['%test%', '%test%']);
+    });
+
+    it('should handle global filter with empty columns (safe behavior)', () => {
+      const options = {
+        columns: [],
+        globalFilter: 'test'
+      };
+      const { sql, params } = buildCountQuery('products', options);
+      assert.strictEqual(sql, 'SELECT COUNT(*) as count FROM "products"');
+      assert.deepStrictEqual(params, []);
+    });
   });
 });